Insulin and insulin-like growth factor-I stimulate a common endogenous phosphoprotein substrate (pp185) in intact neuroblastoma cells

J. Shemer, M. Adamo, G. L. Wilson, D. Heffez, Y. Zick, D. LeRoith

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Abstract

Mouse neuroblastoma N18 cells contain specific high affinity insulin and insulin-like growth factor-I (IGF-I) receptors. Insulin and IGF-I induce phosphorylation, in intact cells, of their respective receptor β subunits. The insulin receptor β subunit is represented by a 95-kDa phosphoprotein that is recognized by a specific antiserum (B10). The IGF-I receptor β subunit is represented by two phosphoproteins of molecular mass 95 and 105 kDa. The hormone-induced phosphorylation was rapid and dose-dependent occurring on both phosphoserine and phosphotyrosine residues. In addition, both insulin and IGF-I induced phosphorylation of an endogenous protein of molecular mass 185 kDa (pp185). The rapidity and dose dependency of the phosphorylation of pp185 suggested that it may represent a common endogenous substrate for the insulin and IGF-I receptors in these neural-derived cells. Phosphorylation was primarily on phosphoserine and phosphotyrosine residues. pp185 did not absorb to wheat germ agglutinin-agarose and was not stimulated by either epidermal growth factor or platelet-derived growth factor. The finding of pp185 in these neural-related cells as well as in non-neural tissues suggests that it may represent a ubiquitous endogenous substrate for both the insulin and IGF-I receptor kinases.

Original languageEnglish (US)
Pages (from-to)15476-15482
Number of pages7
JournalJournal of Biological Chemistry
Volume262
Issue number32
StatePublished - Jan 1 1987
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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