Multiple autophosphorylation sites of the epidermal growth factor receptor are essential for receptor kinase activity and internalization: Contrasting significance of tyrosine 992 in the native and truncated receptors

A. Sorkin, K. Helin, C. M. Waters, G. Carpenter, L. Beguinot

Research output: Contribution to journalArticlepeer-review

150 Scopus citations

Abstract

The role of epidermal growth factor (EGF) receptor autophosphorylation sites in the regulation of receptor functions has been studied using cells transfected with mutant EGF receptors. Simultaneous point mutation of 4 tyrosines (Y1068, Y1086, Y1148, Y1173) to phenylalanine, as well as removal of these sites by truncation of the carboxyl-terminal 123 amino acid residues, resulted in reduced receptor phosphorylation of an in vivo specific substrate phospholipase C-γ1 to less than 50% compared to the wild-type receptor. The internalization rate constant Ke was also significantly lower in these mutants (0.15/min) compared to cells transfected with wild-type receptor (0.27/min). Additional mutation of tyrosine 992 to phenylalanine in the truncated receptor mutant (Dc- 123F) further decreased the receptor internalization rate to a minimal level (ke = 0.07-0.10/min), equivalent to the ke measured for cells expressing kinase-negative receptor (A721). Moreover, tyrosine kinase activity of the Dc-123F receptor toward phospholipase C-γ1, compared to wild-type receptor, was reduced by 90%. Taken together, these results show that EGF receptor lacking five autophosphorylation sites functions similar to a kinase-negative receptor. Mutation of tyrosine residue Y992 alone in the context of full length EGF receptor, however, did not affect receptor internalization or kinase activity toward phospholipase C-γ1. These data indicate that tyrosine 992 is critical for substrate phosphorylation and internalization only in the context of the truncated receptor, and that minor autophosphorylation sites, such as Y992, may act as compensatory regulatory sties in the absence of the major EGF receptor autophosphorylation sites.

Original languageEnglish
Pages (from-to)8672-8678
Number of pages7
JournalJournal of Biological Chemistry
Volume267
Issue number12
StatePublished - Apr 25 1992

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint

Dive into the research topics of 'Multiple autophosphorylation sites of the epidermal growth factor receptor are essential for receptor kinase activity and internalization: Contrasting significance of tyrosine 992 in the native and truncated receptors'. Together they form a unique fingerprint.

Cite this