Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Purification and the immunological characterization of rat protein phosphatase 2A: enzyme levels in diabetic liver and heart

  • 11 Accesses

  • 3 Citations


Protein phosphatase 2A1 was purified from rat skeletal muscle and used to produce antisera to the three subunits of the holoenzyme. Affinity purified antibodies specific for the subunits of the phosphatase enzyme were found to recognize the type 2A1 and 2A2 phosphatase from rat skeletal muscle, heart, liver, brain and erythrocytes and were used to investigate the effects of diabetes on the levels of this enzyme in liver and heart. Phosphorylase phosphatase assays coupled with immunoblot analysis of fractionated rat liver and heart cytosol from normal and diabetic animals show no apparent differences in the quantity or activity of these enzymes following the induction of alloxan diabetes. When considering these results and the normal physiological concentrations of known effectors of these enzymes, it is likely that protein phosphatase 2A1 and 2A2 are not responsible for the dephosphorylation of phosphorylase a under physiological conditions.

This is a preview of subscription content, log in to check access.


  1. 1.

    Edelman AM, Blumenthal DK, Krebs EG: Protein scrinethreonine kinases. Ann Rev Biochem 56: 576–613, 1987

  2. 2.

    Hunter T, Cooper JA: Protein-tyrosine kinases. Ann Rev Biochem 54: 897–930, 1985

  3. 3.

    Cohen P: The structure and regulation of protein phosphatases. Ann Rev Biochem 58: 453–508, 1989

  4. 4.

    Pato MD, Adelstein RS: Dephosphorylation of the 20,000 dalton light chain of myosin by two different phosphatases from smooth muscle. J Biol Chem 255: 6535–6538, 1980

  5. 5.

    Mumby MC, Russell KL, Garrard LJ, Green DD: Cardiac contractile protein phosphatases: purification of two enzyme forms and their characterization with subunit specific antibodies. J Biol Chem 262: 6257–6265, 1987

  6. 6.

    Gilboe DP, Larsen KL, Nuttall FQ: Radioactive method for assay of glycogen phosphorylase. Anal Biochem 47: 20–27, 1972

  7. 7.

    Rulfs J, Jaspers SR, Garnache AK, Miller TB: Phosphorylase synthesis in diabetic hepatocytes and cardiomyocytes. Am J Physiol 257: E74-E80, 1989

  8. 8.

    Tung HYL, Alemany S, Cohen P: The protein phosphatases involved with cellular regulation. 2. purification, subunit structure and properties of protein phosphatases 2A0, 2A1, and 2A2 from rabbit skeletal muscle. Eur J Biochem 148: 253–263, 1985

  9. 9.

    Usui H, Imazu M, Maeta K, Tsukamoto H, Azuma K, Takeda M: Three distinct forms of type 2A protein phosphatase in human erythrocyte cytosol. J Biol Chem 263: 3752–3761, 1988

  10. 10.

    Ingebritsen TS, Stewart AA, Cohen P: The protein phosphatases involved in cellular regulation 6. measurement of type 1 and type 2 protein phosphatases in extracts of mam malian tissues; an assessment of their physiological roles. Eur J Biochem 132: 297–307, 1983

  11. 11.

    Csortos C, Farkas I, Sparks L, Banyasz T, Kovacs T, Gergely P: Phosphorylase phosphatase activities of rat liver in streptozotocin-diabetes. Biochim Biophys Acta 1052: 235–241, 1990

  12. 12.

    Foulkes JG, Jefferson LS: Protein phosphatase-1 and -2A activities in heart, liver and skeletal muscle extracts from control and diabetic rats. Diabetes 33: 576–579, 1984

  13. 13.

    Parsadanian HK, Ter-Tatevosian LP, Martikian HR, Avakian SH: Changes in the activity of enzymes, participating in glycogen metabolism of alloxan diabetic rats. Mol Cell Biochem 90: 185–190, 1989

  14. 14.

    Goris J, Pallen CJ, Parker PJ, Hermann J, Waterfield MD, Merlevede W: Conversion of phosphoseryl/threonyl phosphatase into a phosphotyrosine phosphatase. Biochem J 256: 1029–1034, 1988

  15. 15.

    Ingebritsen TS, Foulkes JG, Cohen P: The broad specificity protein phosphatase from mammalian liver. FEBS Lett 119: 9–15, 1980

  16. 16.

    Khandelwal RL, Enno TL: Purification and characterization of a high molecular weight phosphoprotein phosphatase from rabbit liver. J Biol Chem 260: 14335–14343, 1985

  17. 17.

    DeGuzman A, Lee EYC: Preparation of low-molecular weight forms of rabbit muscle protein phosphatase. Meth Enzymol 159: 356–368, 1988

  18. 18.

    Crouch D, Safer B: Purification and properties of elF 2 phosphatase. J Biol Chem 255: 7918–7924, 1980

  19. 19.

    Sturgill TW, Ray LB, Erickson E, Maller JL: Insulin-stimulated MAP-2 kinase phosphorylates and activates ribosomal protein S6 kinase II. Nature 334: 715–718, 1988

  20. 20.

    Kozma SC, Lane HA, Ferrari S, Luther H, Siegmann M, Thomas G: A stimulated S6 kinase from rat liver: identity with the mitogen activated S6 kinase of 3T3 cells. EMBO J 8: 4125–4132, 1989

  21. 21.

    Gregory JS, Boulton TG, Sang B-C, Cobb MH: An insulin stimulated ribosomal S6 kinase from rabbit liver. J Biol Chem 264: 18397–18401, 1989

  22. 22.

    Virshup DM, Kauffmann MG, Kelly TJ: Activation of SV 40 DNA replication in vitro by cellular protein phosphatase 2A. EMBO J 8: 3891–3898, 1989

  23. 23.

    Pallas DC, Shahrik LK, Martin BL, Jaspers S, Miller TB, Brautigan DL, Roberts TM: Polyoma small and middle T antigens and SV 40 small t antigen form stable complexes with protein phosphatase 2A. Cell 60: 167–176, 1990

Download references

Author information

Correspondence to Stephen R. Jaspers.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Jaspers, S.R., Miller, T.B. Purification and the immunological characterization of rat protein phosphatase 2A: enzyme levels in diabetic liver and heart. Mol Cell Biochem 101, 167–174 (1991). https://doi.org/10.1007/BF00229533

Download citation

Key words

  • rat protein phosphatase 2A
  • liver
  • heart
  • diabetes