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  • 1.
    Bergström, Gunnel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Dahlqvist, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Humble, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Subtilisin-catalyzed removal of phosphorylated site of pig liver pyruvate kinase without inactivation of the enzyme1975In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 56, no 2, p. 288-291Article in journal (Refereed)
  • 2.
    Dahlqvist, Ulla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Endogenous substrates of protein kinase in rat liver cell sap under different dietary conditions1978In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 540, no 1, p. 13-23Article in journal (Refereed)
    Abstract [en]

    Liver cell sap from normally fed rats, rats fed with a high-carbohydrate diet and fasted rats was chromatographed on DEAE-cellulose (pH 7.0). The chromatogram from each diet group was analyzed for pyruvate kinase activity and endogenous substrates of cyclic AMP-stimulated protein kinase. The materials were pooled into five phosphorylatable fractions, in each of which phosphate incorporation at 0.1 mM and 1.0 mM [32P]ATP in the presence of cyclic AMP and protein kinase was determined. For characterization of the phosphorylatable components, thin-layer gel chromatography on Sephadex G-200 and polyacrylamide gel electrophoresis in detergent were used for determination of native and minimal molecular weights, respectively. Except for pyruvate kinase, eight components which incorporated at least 0.05 nmol of [32P]phosphate/g of liver were detected. The phosphorylation of four of them was stimulated by cyclic AMP. Their minimal molecular weights were 42000, 21000, 52000 and 49000. The component with a minimal molecular weight of 42000 seemed to have a native molecular weight of 160000. Both the 21000 and the 52000 component had a native molecular weight of about 110000-120000. The protein with a minimal molecular weight of 49000 could not be correlated with certainty to a native molecular weight. The proteins whose phosphorylation was not stimulated by cyclic AMP had minimal molecular weights of 54000, 39000, 34000 and 22000.

  • 3.
    Dahlqvist-Edberg, Ulla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Purification of a Ca2+-activated protease from rat erythrocytes and its possible effect on pyruvate kinase in vivo1981In: Biochimica et Biophysica Acta-Enzymology, ISSN 0005-2744, Vol. 660, no 1, p. 96-101Article in journal (Refereed)
    Abstract [en]

    A Ca2+-activated protease with [32P]phosphopyruvate kinase as substrate was purified to about 50% from rat erythrocytes. The purification involved chromatography on Sepharose/Sephadex gels, DEAE-cellulose and (NH4)2SO4 precipitation. The protease required 3.3 mM Ca2+ for full activity. When pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40) was purified from erythrocytes incubated with [32P]phosphate it contained 0.5 mol [32P]phosphate/mol enzyme subunit. When 3.3 mM Ca2+ were added at hemolysis this incorporation decreased. The possible importance of this Ca2+-activated protease for the regulation of pyruvate kinase in erythrocytes is discussed.

  • 4.
    Dahlqvist-Edberg, Ulla
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Wretborn, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    The demonstration in rat liver cell sap of protein kinase and phosphoprotein phosphatase active on fructose-bisphosphatase1982In: Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology, ISSN 0167-4838, E-ISSN 1879-2588, Vol. 706, no 2, p. 239-244Article in journal (Refereed)
    Abstract [en]

    A protein kinase active on fructose-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) was demonstrated in rat liver cell sap. The protein kinase activity was stimulated by cyclic AMP and coincided with the activity of cyclic AMP-dependent protein kinase type I. In addition, three different peaks of phosphoprotein phosphatase active on [32P] phosphofructose-bisphosphatase were found on chromatography of rat liver cell sap on a DEAE-cellulose column. These phosphatases needed divalent cations for full activity. 5'-AMP, a negative modulator of fructose-bisphosphatase, had no effect on the phosphorylation-de-phosphorylation reactions of the enzyme. ATP and Ca2+ did not influence the dephosphorylation reaction of fructose-bisphosphatase.

  • 5.
    Edlund, Bror
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Andersson, Jill
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Titanji, Vincent
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Dahlqvist, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Amino acid sequence at the phosphorylated site of rat liver pyruvate kinase1975In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 67, no 4, p. 1516-1521Article in journal (Refereed)
    Abstract [en]

    One dominating peptic phosphopeptide, Asx-Thr-Lys-Gly-Pro-Glx-Ile-Glx-Thr-Gly-Val-Leu-Arg-Arg-Ala-(32P)SerP-Val-Ala-Glx-Leu, was obtained from rat liver pyruvate kinase (type L) phosphorylated by cyclic 3′,5′-AMP-stimulated protein kinase from the same tissue. The sequence around the phosphorylated serine residue is similar to that of a corresponding but smaller peptic phosphopeptide previously isolated from pig liver (type L) pyruvate kinase, Leu-Arg-Arg-Ala-(32P)SerP-Leu.

  • 6.
    Ek, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Dahlqvist, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Humble, Elisabet
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Comparative kinetic studies on the L-type pyruvate kinase from rat liver and the enzyme phosphorylated by cyclic 3´, 5´-AMP-stimulated protein kinase1976In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 429, no 2, p. 374-382Article in journal (Refereed)
    Abstract [en]

    The kinetics of rat liver L-type pyruvate kinase (EC 2.7.1.40), phosphorylated with cyclic AMP-stimulated protein kinase from the same source, and the unphosphorylated enzyme have been compared. The effects of pH and various concentrations of substrates, Mg2+, K+ and modifiers were studied. In the absence of fructose 1, 6-diphosphate at pH 7.3, the phosphorylated pyruvate kinase appeared to have a lower affinity for phosphoenolpyruvate (K0.5=0.8 mM) than the unphosphorylated enzyme (K0.5=0.3 mM). The enzyme activity vs. phosphoenolpyruvate concentration curve was more sigmoidal for the phosphorylated enzyme with a Hill coefficient of 2.6 compared to 1.6 for the unphosphorylated enzyme. Fructose 1, 6-diphosphate increased the apparent affinity of both enzyme forms for phosphoenolpyruvate. At saturating concentrations of this activator, the kinetics of both enzyme forms were transformed to approximately the same hyperbolic curve, with a Hill coefficient of 1.0 and K0.5 of about 0.04 mM for phosphoenolpyruvate. The apparent affinity of the enzyme for fructose 1, 6-diphosphate was high at 0.2 mM phosphoenolpyruvate with a K0.5=0.06 muM for the unphosphorylated pyruvate kinase and 0.13 muM for the phosphorylated enzyme. However, in the presence of 0.5 mM alanine plus 1.5 mM ATP, a higher fructose 1, 6-diphosphate concentration was needed for activation, with K0.5 of 0.4 muM for the unphosphorylated enzyme and of 1.4 muM for the phosphorylated enzyme. The results obtained strongly indicate that phosphorylation of pyruvate kinase may also inhibit the enzyme in vivo. Such an inhibition should be important during gluconeogenesis.

  • 7.
    Ek, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Dahlqvist-Edberg, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    The kinetics of unphosphorylated, phosphorylated and proteolytically modified fructose bisphosphatase from rat liver1981In: Biochimica et Biophysica Acta, ISSN 0005-2744, Vol. 662, no 2, p. 265-270Article in journal (Refereed)
    Abstract [en]

    Phosphorylation of fructose-bisphosphatase (D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) by the catalytic subunit of cyclic AMP-dependent protein kinase from pig muscle decreased the K0.5 for fructose-bisphosphate from 21 to 11 microM. When the phosphorylated fructose-bisphosphatase was treated with trypsin the K0.5 increased to 22 microM. The K0.5 also increased when the phosphoenzyme was treated with a partially purified phosphatase from rat liver. There was no difference between the unphosphorylated and phosphorylated enzyme with respect to pH dependence, the pH optimum being about 7.0 for both. Limited treatment of fructose-bis-phosphatase with subtilisin, which cleaves the enzyme at its unphosphorylatable N-terminal part, increased the pH optimum more than limited treatment with trypsin, which releases the phosphorylated peptide at the C-terminal part of fructose-bisphosphatase. The phosphorylated site on the phosphorylated fructose-bisphosphatase was more easily split off by trypsin treatment than the corresponding unphosphorylated site. The results suggest in addition to the glucagon-induced phosphorylation of fructose-bisphosphatase described by Claus et al. [1] that the phosphorylation-dephosphorylation of fructose-bisphosphatase could be of importance for the hormonal regulation of the enzyme in vivo.

  • 8.
    Ek, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Phosphohistidine phosphatase 1 (PHPT1) also dephosphorylates phospholysine of chemically phosphorylated histone H1 and polylysine2015In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 120, no 1, p. 20-27Article in journal (Refereed)
    Abstract [en]

    Background. Phosphohistidine phosphatase 1 (PHPT1), also named protein histidine phosphatase (PHP), is a eukaryotic enzyme dephosphorylating proteins and peptides that are phosphorylated on a histidine residue. A preliminary finding that histone H1, which lacks histidine, was phosphorylated by phosphoramidate and dephosphorylated by PHPT1 prompted the present investigation. Methods. Histone H1 and polylysine were phosphorylated at a low concentration (3.9 mM) of phosphoramidate. Their dephosphorylation by recombinant human PHPT1 was investigated by using a DEAE-Sepharose spin column technique earlier developed by us for studies on basic phosphoproteins and phosphopeptides. Determination of protein-bound, acid-labile phosphate was performed by a malachite green method. Mass spectrometry (MS) was used to investigate the occurrence of N-epsilon-phospholysine residues in a phosphorylated histone H 1.2 preparation, and to measure the activity of PHPT1 against free N-omega-phosphoarginine. Results. Histone H1.2, which lacks histidine, was phosphorylated by phosphoramidate on several lysine residues, as shown by MS. PHPT1 was shown to dephosphorylate phosphohistone H1 at a rate similar to that previously described for the dephosphorylation of phosphohistidine-containing peptides. In addition, phosphopolylysine was an equally good substrate for PHPT1. However, no dephosphorylation of free phosphoarginine by PHPT1 could be detected. Conclusion. The finding that PHPT1 can dephosphorylate phospholysine in chemically phosphorylated histone H1 and polylysine demonstrates a broader specificity for this enzyme than known so far.

  • 9.
    Ek, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Malm, Johan
    Lilja, Hans
    Carlsson, Lena
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Ronquist, Gunnar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Exogenous protein kinases A and C, but not endogenous prostasome-associated protein kinase, phosphorylate semenogelins I and II from human semen2002In: Journal of Andrology, ISSN 0196-3635, E-ISSN 1939-4640, Vol. 23, no 6, p. 806-814Article in journal (Refereed)
    Abstract [en]

    Semenogelins I and II are the quantitatively dominating proteinsin humansemen. They comprise the major part of the sperm-entrappinggel formed atejaculation, which subsequently liquefies dueto proteolysis of thegel-forming proteins by prostate-specificantigen (PSA). The mechanism behindgel formation and its physiologicalsignificance is not known. We have studiedphosphorylation anddephosphorylation of human semenogelins. Both werephosphorylatedby protein kinases A and C (PKA and PKC, respectively) at arateabout 5 times less than that of histone. For PKA, incorporated(32P)phosphateinto semenogelin approached a maximum above 1mol/mol. Correspondingvalues for phosphorylation of the semenogelins with PKCweregreater than 10. There was no change in the sensitivity ofphosphosemenogelinsto proteolysis by PSA. Serine (PKA) and serine andthreonine(PKC) were the phosphate-accepting amino acid residues, andallincorporated (32P)phosphate could be removed from the semenogelinswithhuman acid phosphatase. Nil or very little phosphate could bedetected inpurified semenogelins isolated from seminal plasma.In vivo, about half theprotein kinase activity in seminal plasmawas bound to prostasomes. PKA butnot PKC purified from prostasomescould phosphorylate specific substrates, butthey could phosphorylateeither of the semenogelins.

  • 10.
    Ek, Pia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Li, Jin-Ping
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Pettersson, Gunilla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Gong, Feng
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Identification and characterization of a mammalian 14-kDa phosphohistidine phosphatase2002In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 269, p. 5016-5023Article in journal (Refereed)
    Abstract [en]

    Protein histidine phosphorylation in eukaryotes has beensparsely studied compared to protein serine/threonine andtyrosine phosphorylation. In an attempt to rectify this byprobing porcine liver cytosol with the phosphohistidinecontainingpeptide succinyl-Ala-His(P)-Pro-Phe-p-nitroanilide(phosphopeptide I), we observed a phosphataseactivity that was insensitive towards okadaic acid andEDTA. This suggested the existence of a phosphohistidinephosphatase different from protein phosphatase 1, 2Aand 2C. A 1000-fold purification to apparent homogeneitygave a 14-kDa phosphatase with a specific activity of 3lmolÆmin)1Æmg)1 at pH 7.5 with 7 lM phosphopeptide Ias substrate. Partial amino-acid sequence determination ofthe purified porcine enzyme by MS revealed similaritywith a human sequence representing a human chromosome9 gene of hitherto unknown function. Molecularcloning from a human embryonic kidney cell cDNAlibraryfollowed by expression and purification, yielded aprotein with a molecular mass of 13 700 Da, and anEDTA-insensitive phosphohistidine phosphatase activityof 9 lmolÆmin)1Æmg)1 towards phosphopeptide I. Nodetectable activity was obtained towards a set of phosphoserine-,phosphothreonine-, and phosphotyrosine peptides.Northern blot analysis indicated that the humanphosphohistidine phosphatase mRNA was present preferentiallyin heart and skeletal muscle. These resultsprovide a new tool for studying eukaryotic histidinephosphorylation/dephosphorylation.

  • 11.
    Engström, Lorentz
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ragnarsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Dahlqvist-Edberg, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    The cyclic AMP-dependent phosphorylation of pyruvate kinase as a model in the study of regulation and turnover of phosphorylated proteins1982In: Progress in clinical and biological research, ISSN 0361-7742, Vol. 102, no Pt C, p. 203-212Article in journal (Refereed)
  • 12.
    Humble, Elisabet
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Dahlqvist-Edberg, Ulla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Netzel, Elvy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ragnarsson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Engström, Lorentz
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Amino acid sequence at the phosphorylated site of rat liver fructose-1,6-diphosphatase and phosphorylation of a corresponding synthetic peptide1979In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 90, no 3, p. 1064-1072Article in journal (Refereed)
    Abstract [en]

    Rat liver fructose-1,6-diphosphatase was phosphorylated with (32P)ATP and the catalytic subunit of cyclic AMP-dependent protein kinase from pig muscle. After digestion with pepsin, α-chymotrypsin and subtilisin a peptide with the amino-terminal sequence Ser-Arg-Tyr-(32P)SerP-Leu-Pro-Leu-Pro was isolated. A synthetic unphosphorylated heptapeptide with the same amino acid sequence, ending with leucine, was phosphorylated with an apparent Km of 400 μM, while the apparent Km value for fructose-1,6-diphosphatase was 30 μM (subunit concentration). The Vmax value was 20 times higher for the peptide than for the enzyme.

  • 13.
    Inturi, Raviteja
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Wäneskog, Marcus
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Vlachakis, Dimitrios
    Ali, Yeasmeen
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Punga, Tanel
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Bjerling, Pernilla
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    A splice variant of the human phosphohistidine phosphatase 1 (PHPT1) is degraded by the proteasome2014In: International Journal of Biochemistry and Cell Biology, ISSN 1357-2725, E-ISSN 1878-5875, Vol. 57, p. 69-75Article in journal (Refereed)
    Abstract [en]

    Regulation of protein activity by phosphorylation is central in many cellular processes. Phosphorylation of serine, threonine and tyrosine residues is well documented and studied. In addition, other amino acids, like histidine can be phosphorylated, but neither the mechanism nor the function of this modification is well understood. Nevertheless, there is a 14 kDa enzyme with phosphohistidine phosphatase activity, named PHPT1, found in most animals, but not in bacteria, plant or fungi. There are a few splice variant transcripts formed from the human PHPT1 locus and some of them are predicted to form variant proteins, but studies of these proteins are lacking. In order to get insight into the possible function of the variant transcripts encoded at the PHPT1 locus, ectopic expression of PHPT1 transcript variant 6, predicted to be degraded by the non-sense mediated mRNA decay pathway, in HeLa cells was undertaken. In HeLa cells the splice variant protein was degraded by the proteasome, unlike the wild type protein. Using an in silico modeling approach the variant C-terminal end of the proteins were predicted to form different secondary structures that might explain the different properties of the two proteins. The specific degradation of the PHPT1 splice variant indicates that at least for the PHPT1 protein, the quality control and the self-guarding of the cellular system works at two levels, first at the RNA level, aberrant transcripts are degraded by the non-sense mediated mRNA decay pathway, and the small amount of proteins that are formed will be degraded by the proteasome.

  • 14.
    Loog, Mart
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Bo
    Oskolkov, Nikita
    Narvanen, Ale
    Järv, Jaak
    Ek, Pia
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Screening for the optimal specificity profile of protein kinase C using electrospray mass-spectrometry.2005In: J Biomol Screen, ISSN 1087-0571, Vol. 10, no 4, p. 320-8Article in journal (Refereed)
  • 15.
    Loog, Mart
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Oskolkov, Nikita
    O'Farrell, Fergal
    Ek, Pia
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Järv, Jaak
    Comparison of cAMP-dependent protein kinase substrate specificity in reaction with proteins and synthetic peptides.2005In: Biochim Biophys Acta, ISSN 0006-3002, Vol. 1747, no 2, p. 261-6Article in journal (Refereed)
  • 16.
    Ma, Ruixin
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Kanders, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Sundh, Ulla Beckman
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Geng, Meiyu
    Ek, Pia
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Zetterqvist, Örjan
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Li, Jin-Ping
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Mutational study of human phosphohistidine phosphatase: effect on enzymatic activity.2005In: Biochem Biophys Res Commun, ISSN 0006-291X, Vol. 337, no 3, p. 887-91Article in journal (Refereed)
  • 17.
    Marknell DeWitt, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Lundgren, Thomas
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Lidholm, Jonas
    Adaptation of the major latex allergen Hev b 5 for large scale production utilizing a synthetic gene approachManuscript (Other academic)
  • 18.
    Tavoosidana, Gholamreza
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Ronquist, Gunnar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Darmanis, Spyros
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Yan, Junhong
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular tools. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Carlsson, Lena
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Wu, Di
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular tools. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Conze, Tim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Semjonow, Axel
    Prostate Center, Dept. of Urology, University Clinic, Muenster, Germany.
    Eltze, Elke
    Prostate Center, Gerhard-Domagk Institute of Pathology, University Clinic, Muenster, Germany.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Landegren, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular tools. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kamali-Moghaddam, Masood
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Multiple recognition assay reveals prostasomes as promising plasma biomarkers for prostate cancer2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 21, p. 8809-8814Article in journal (Refereed)
    Abstract [en]

    Prostasomes are microvesicles (mean diameter, 150 nm) that are produced and secreted by normal and malignant prostate acinar cells. It has been hypothesized that invasive growth of malignant prostate cells may cause these microvesicles, normally released into seminal fluid, to appear in interstitial space and therewith into peripheral circulation. The suitability of prostasomes as blood biomarkers in patients with prostate cancer was tested by using an expanded variant of the proximity ligation assay (PLA). We developed an extremely sensitive and specific assay (4PLA) for detection of complex target structures such as microvesicles in which the target is first captured via an immobilized antibody and subsequently detected by using four other antibodies with attached DNA strands. The requirement for coincident binding by five antibodies to generate an amplifiable reporter results in both increased specificity and sensitivity. The assay successfully detected significantly elevated levels of prostasomes in blood samples from patients with prostate cancer before radical prostatectomy, compared with controls and men with benign biopsy results. The medians for prostasome levels in blood plasma of patients with prostate cancer were 2.5 to sevenfold higher compared with control samples in two independent studies, and the assay also distinguished patients with high and medium prostatectomy Gleason scores (8/9 and 7, respectively) from those with low score (<= 6), thus reflecting disease aggressiveness. This approach that enables detection of prostasomes in peripheral blood may be useful for early diagnosis and assessment of prognosis in organ-confined prostate cancer.

  • 19.
    Zhang, X-Q
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Sundh, Ulla Beckman
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Jansson, Leif
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Zetterqvist, Örjan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Ek, Pia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Immunohistochemical localization of phosphohistidine phosphatase PHPT1 in mouse and human tissues2009In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 114, no 2, p. 65-72Article in journal (Refereed)
    Abstract [en]

    Protein histidine phosphorylation accounts for about 6% of the total protein phosphorylation in eukaryotic cells; still details concerning histidine phosphorylation and dephosphorylation are limited. A mammalian 14-kDa phosphohistidine phosphatase, also denominated PHPT1, was found 6 years ago that provided a new tool in the study of phosphohistidine phosphorylation. The localization of PHPT1 mRNA by Northern blot analysis revealed high expression in heart and skeletal muscle. The main object of the present study was to determine the PHPT1 expression on protein level in mouse tissues in order to get further information on the physiological role of the enzyme. Tissue samples from adult mice and 14.5-day-old mouse embryos were processed for immunostaining using a PHPT1-specific polyclonal antibody. The same antibody was also provided to the Swedish human protein atlas project (HPR) (http://www.proteinatlas.org/index.php). The results from both studies were essentially consistent with the previously reported expression of mRNA of a few human tissues. In addition, several other tissues, including testis, displayed a high protein expression. A salient result of the present investigation was the ubiquitous expression of the PHPT1 protein and its high expression in continuously dividing epithelial cells.

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