Modulation of the activity of purified phosphatidylinositol 4-phosphate kinase by phosphorylated and dephosphorylated B-50 protein

Biochem Biophys Res Commun. 1985 May 16;128(3):1219-27. doi: 10.1016/0006-291x(85)91070-8.

Abstract

To investigate the modulation of phosphatidylinositol 4-phosphate kinase activity by the degree of phosphorylation of the B-50 protein, the enzyme was purified from rat brain cytosol by ammonium sulphate precipitation and DEAE-cellulose column chromatography. Purified rat brain B-50 was phosphorylated with protein kinase C and dephosphorylated with alkaline phosphatase. Incubation of the semi-purified phosphatidylinositol 4-phosphate kinase with 1 microgram of the B-50 preparation enriched in the dephospho-form, resulted in a small reduction of phosphatidylinositol 4-phosphate kinase activity (-16%), whereas incubation with the phospho B-50 preparation inhibited the enzyme activity by 40%. The effect of exogenous B-50 was studied in the presence of 10 micrograms albumin to minimize aspecific protein-protein interactions. The present data on the effect of exogenous B-50 protein on phosphatidylinositol 4-phosphate kinase activity, further support our hypothesis that the phosphorylation state of B-50 may be a regulatory factor in phosphoinositide metabolism in rat brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Albumins / pharmacology
  • Animals
  • Brain / metabolism
  • Cytosol / metabolism
  • GAP-43 Protein
  • In Vitro Techniques
  • Male
  • Nerve Tissue Proteins / pharmacology*
  • Phosphatidylinositols / metabolism
  • Phosphorylation
  • Phosphotransferases (Alcohol Group Acceptor)*
  • Phosphotransferases / antagonists & inhibitors
  • Phosphotransferases / metabolism*
  • Rats

Substances

  • Albumins
  • GAP-43 Protein
  • Nerve Tissue Proteins
  • Phosphatidylinositols
  • Phosphotransferases
  • Phosphotransferases (Alcohol Group Acceptor)
  • 1-phosphatidylinositol-4-phosphate 5-kinase