Phospholipid activation of the insulin receptor kinase: Regulation by phosphatidylinositol

L. J. Sweet, D. T. Dudley, J. E. Pessin, A. A. Spector

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

A soybean phospholipid mixture produced a concentration-dependent enhancement of β subunit autophosphorylation of the detergent-soluble, purified human placental insulin receptor. Although phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine also increased insulin receptor autophosphorylation, only phosphatidylinositol (PtdIns) stimulated to a similar extent as the phospholipid mixture. The effect of PtdIns was biphasic, stimulating at low concentrations (75 μM), but having no stimulatory effect at high concentrations (1.0 mM). Phospholipids also stimulated the exogenous protein kinase activity of the insulin receptor toward histone H2B. Phosphorylation of PtdIns occurrd with these purified insulin receptor preparations, but this activity was insulin-independent, and the turnover number for PtdIns phosphorylation in the presence of soybean phospholipid was 1/220th as small as the turnover number for the autophosphorylating activity. These results suggest that although PtdIns can modulate the activity of the insulin receptor kinase, PtdIns phosphorylation itself is not directly involved in this regulation.

Original languageEnglish (US)
Pages (from-to)55-59
Number of pages5
JournalFASEB Journal
Volume1
Issue number1
DOIs
StatePublished - 1987

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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