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. 1996 Apr 1;315(Pt 1):91–96. doi: 10.1042/bj3150091

Time-dependent pseudo-activation of hepatic glycogen synthase b by glucose 6-phosphate without involvement of protein phosphatases.

S Wera 1, M Bollen 1, L Moens 1, W Stalmans 1
PMCID: PMC1217201  PMID: 8670137

Abstract

During a 30 min incubation at 25 degrees C in the presence of 5-10 mM glucose 6-phosphate, pure glycogen-bound glycogen synthase b from dog liver was progressively converted into a form that was fully catalytically active in the presence of 10 mM Na2SO4 plus 0.5 mM glucose 6-phosphate. The latter enzyme was unlike synthase a (which does not require glucose 6-phosphate for activity), and unlike synthase b (which is strongly inhibited by sulphate). The conversion was insensitive to various inhibitors of Ser/Thr-protein phosphatases and alkaline phosphatases, and was therefore termed 'pseudo-activation'. Kinetically, pseudo-activation increased the V(max) 4-fold without affecting the K(m) for the substrate UDP-glucose. Pseudo-activation appeared to be an irreversible process, but several lines of evidence argue against a limited proteolysis. Pseudo-activation of glycogen synthase occurred also readily in a rat liver cytosol, but it was not observed with purified synthase from skeletal muscle. These observations have important implications for the assay of liver gycogen-synthase phosphatase; the possible physiological implications remain to be explored.

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Selected References

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  1. Agostinis P., Marin O., James P., Hendrix P., Merlevede W., Vandenheede J. R., Pinna L. A. Phosphorylation of the phosphatase modulator subunit (inhibitor-2) by casein kinase-1. Identification of the phosphorylation sites. FEBS Lett. 1992 Jun 29;305(2):121–124. doi: 10.1016/0014-5793(92)80877-j. [DOI] [PubMed] [Google Scholar]
  2. Bai G., Zhang Z. J., Werner R., Nuttall F. Q., Tan A. W., Lee E. Y. The primary structure of rat liver glycogen synthase deduced by cDNA cloning. Absence of phosphorylation sites 1a and 1b. J Biol Chem. 1990 May 15;265(14):7843–7848. [PubMed] [Google Scholar]
  3. Bollen M., Stalmans W. The structure, role, and regulation of type 1 protein phosphatases. Crit Rev Biochem Mol Biol. 1992;27(3):227–281. doi: 10.3109/10409239209082564. [DOI] [PubMed] [Google Scholar]
  4. Camici M., DePaoli-Roach A. A., Roach P. J. Rabbit liver glycogen synthase. Susceptibility of the enzyme subunit to proteolysis. J Biol Chem. 1982 Sep 10;257(17):9898–9901. [PubMed] [Google Scholar]
  5. Carabaza A., Ciudad C. J., Baqué S., Guinovart J. J. Glucose has to be phosphorylated to activate glycogen synthase, but not to inactivate glycogen phosphorylase in hepatocytes. FEBS Lett. 1992 Jan 20;296(2):211–214. doi: 10.1016/0014-5793(92)80381-p. [DOI] [PubMed] [Google Scholar]
  6. Cohen P. The structure and regulation of protein phosphatases. Annu Rev Biochem. 1989;58:453–508. doi: 10.1146/annurev.bi.58.070189.002321. [DOI] [PubMed] [Google Scholar]
  7. Depaoli-Roach A. A., Park I. K., Cerovsky V., Csortos C., Durbin S. D., Kuntz M. J., Sitikov A., Tang P. M., Verin A., Zolnierowicz S. Serine/threonine protein phosphatases in the control of cell function. Adv Enzyme Regul. 1994;34:199–224. doi: 10.1016/0065-2571(94)90017-5. [DOI] [PubMed] [Google Scholar]
  8. Doperé F., Vanstapel F., Stalmans W. Glycogen-synthase phosphatase activity in rat liver. Two protein components and their requirement for the activation of different types of substrate. Eur J Biochem. 1980 Feb;104(1):137–146. doi: 10.1111/j.1432-1033.1980.tb04409.x. [DOI] [PubMed] [Google Scholar]
  9. Hewick R. M., Hunkapiller M. W., Hood L. E., Dreyer W. J. A gas-liquid solid phase peptide and protein sequenator. J Biol Chem. 1981 Aug 10;256(15):7990–7997. [PubMed] [Google Scholar]
  10. Huang T. S., Krebs E. G. Effect of proteases on the structure and activity of rabbit skeletal muscle glycogen synthetase. FEBS Lett. 1979 Feb 1;98(1):66–70. doi: 10.1016/0014-5793(79)80153-2. [DOI] [PubMed] [Google Scholar]
  11. Hubbard M. J., Cohen P. On target with a new mechanism for the regulation of protein phosphorylation. Trends Biochem Sci. 1993 May;18(5):172–177. doi: 10.1016/0968-0004(93)90109-z. [DOI] [PubMed] [Google Scholar]
  12. Hunkapiller M. W., Lujan E., Ostrander F., Hood L. E. Isolation of microgram quantities of proteins from polyacrylamide gels for amino acid sequence analysis. Methods Enzymol. 1983;91:227–236. doi: 10.1016/s0076-6879(83)91019-4. [DOI] [PubMed] [Google Scholar]
  13. Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
  14. Landt M., Boltz S. C., Butler L. G. Alkaline phosphatase: affinity chromatography and inhibition by phosphonic acids. Biochemistry. 1978 Mar 7;17(5):915–919. doi: 10.1021/bi00598a027. [DOI] [PubMed] [Google Scholar]
  15. Massillon D., Bollen M., De Wulf H., Overloop K., Vanstapel F., Van Hecke P., Stalmans W. Demonstration of a glycogen/glucose 1-phosphate cycle in hepatocytes from fasted rats. Selective inactivation of phosphorylase by 2-deoxy-2-fluoro-alpha-D-glucopyranosyl fluoride. J Biol Chem. 1995 Aug 18;270(33):19351–19356. doi: 10.1074/jbc.270.33.19351. [DOI] [PubMed] [Google Scholar]
  16. Matsudaira P. Sequence from picomole quantities of proteins electroblotted onto polyvinylidene difluoride membranes. J Biol Chem. 1987 Jul 25;262(21):10035–10038. [PubMed] [Google Scholar]
  17. Roach P. J. Control of glycogen synthase by hierarchal protein phosphorylation. FASEB J. 1990 Sep;4(12):2961–2968. [PubMed] [Google Scholar]
  18. Sivaramakrishnan S., Vandenheede J. R., Merlevede W. Characterization of different forms of kinase FA from rabbit skeletal muscle. Adv Enzyme Regul. 1983;21:321–330. doi: 10.1016/0065-2571(83)90021-3. [DOI] [PubMed] [Google Scholar]
  19. Soderling T. R. Regulation of glycogen synthetase. Effects of trypsin on the structure, activity, and phosphorylation of the skeletal muscle enzyme. J Biol Chem. 1976 Jul 25;251(14):4359–4364. [PubMed] [Google Scholar]
  20. Stalmans W., Bollen M., Mvumbi L. Control of glycogen synthesis in health and disease. Diabetes Metab Rev. 1987 Jan;3(1):127–161. doi: 10.1002/dmr.5610030107. [DOI] [PubMed] [Google Scholar]
  21. Staneloni R. J., Piras R. Reversible aggregation of muscle glycogen synthetase by metabolites. Biochem Biophys Res Commun. 1971 Jan 22;42(2):237–244. doi: 10.1016/0006-291x(71)90093-3. [DOI] [PubMed] [Google Scholar]
  22. Takeda Y., Brewer H. B., Jr, Larner J. Structural studies on rabbit muscle glycogen synthase. I. Subunit composition. J Biol Chem. 1975 Dec 10;250(23):8943–8950. [PubMed] [Google Scholar]
  23. Takeda Y., Larner J. Structural studies on rabbit muscle glycogen synthase. II. Limited proteolysis. J Biol Chem. 1975 Dec 10;250(23):8951–8956. [PubMed] [Google Scholar]
  24. Tan A. W., Nuttall F. Q. Endogenous phosphates on liver glycogen synthase D and synthase I. Studies on the number and location. J Biol Chem. 1983 Aug 25;258(16):9624–9630. [PubMed] [Google Scholar]
  25. Villar-Palasi C. Inhibition by glucose 6-phosphate of cyclic AMP-dependent protein kinase phosphorylation of glycogen synthase. Biochim Biophys Acta. 1994 Jul 20;1207(1):88–92. doi: 10.1016/0167-4838(94)90055-8. [DOI] [PubMed] [Google Scholar]
  26. Villar-Palasi C. Substrate specific activation by glucose 6-phosphate of the dephosphorylation of muscle glycogen synthase. Biochim Biophys Acta. 1991 Nov 12;1095(3):261–267. doi: 10.1016/0167-4889(91)90109-b. [DOI] [PubMed] [Google Scholar]
  27. Wera S., Bollen M., Stalmans W. Purification and characterization of the glycogen-bound protein phosphatase from rat liver. J Biol Chem. 1991 Jan 5;266(1):339–345. [PubMed] [Google Scholar]
  28. de Wulf H., Hers H. G. The influence of inorganic phosphate, adenosine triphosphate and glucose 6-phosphate on the activity of liver glycogen synthetase. Eur J Biochem. 1968 Dec 5;6(4):545–551. doi: 10.1111/j.1432-1033.1968.tb00479.x. [DOI] [PubMed] [Google Scholar]

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