Phosphorylase phosphatase activities of rat liver in streptozotocin-diabetes

C. Csortos, Ilona Farkas, Lloyd Sparks, Tamás Bányász, Tibor Kovács, P. Gergely

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Protein phosphatase-1 and 2A, accounting for all the hepatic activity regulating phosphorylase, were assayed in streptozotocin-induced (8 weeks) diabetic Wistar rats. Cytosolic protein phosphatase-1 and 2A were distinguished by chromatography on heparin-Sepharose and by inhibition with inhibitor-2. Approx. 25-35% increases in type-1 phosphorylase phosphatase activity measured in cytosols were registered in diabetic rats when compared with control and 24 h fasting animals. The enrichment of protein phosphatase-1 in the cytosol of streptozotocin-treated rat livers could not be attributed to the reduced glycogen content with the onset of diabetes, since this elevated level of type-1 phosphatase was not observed in fasting rats with low glycogen content. The translocation of type-1 phosphatase from the particulate fraction into the cytosol was also recorded in trypsin-treated samples of diabetic rat livers. The apparent molecular weight of type-1 phosphatase in the cytosol of control and fasted rats was 160 000 as judged by gel filtration. The type-1 phosphatase activity that was released from the particulate fraction by streptozotocin-induced diabetes identified a further enzyme species (Mr 110 000) in the cytosol. Our data imply that the higher levels of cytosolic protein phosphatase-1 in diabetic rat liver could be a consequence of the dissociation of the catalytic subunit of protein phosphatase-1 and the glycogen-binding subunit in rat livers.

Original languageEnglish
Pages (from-to)235-241
Number of pages7
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Volume1052
Issue number1
DOIs
Publication statusPublished - Apr 9 1990

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Phosphorylase Phosphatase
Experimental Diabetes Mellitus
Protein Phosphatase 1
Cytosol
Liver
Phosphoric Monoester Hydrolases
Glycogen
Protein Phosphatase 2
Streptozocin
Fasting
Phosphorylases
Trypsin
Gel Chromatography
Chromatography
Wistar Rats
Molecular Weight

Keywords

  • (Rat liver)
  • Diabetes
  • Fasting
  • Hepatic metabolism
  • Protein phosphatase
  • Streptozotocin

ASJC Scopus subject areas

  • Biophysics
  • Cell Biology
  • Molecular Biology

Cite this

Phosphorylase phosphatase activities of rat liver in streptozotocin-diabetes. / Csortos, C.; Farkas, Ilona; Sparks, Lloyd; Bányász, Tamás; Kovács, Tibor; Gergely, P.

In: Biochimica et Biophysica Acta - Molecular Cell Research, Vol. 1052, No. 1, 09.04.1990, p. 235-241.

Research output: Contribution to journalArticle

Csortos, C. ; Farkas, Ilona ; Sparks, Lloyd ; Bányász, Tamás ; Kovács, Tibor ; Gergely, P. / Phosphorylase phosphatase activities of rat liver in streptozotocin-diabetes. In: Biochimica et Biophysica Acta - Molecular Cell Research. 1990 ; Vol. 1052, No. 1. pp. 235-241.
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