Replacement of the Conserved Tyrosine 1210 by Phenylalanine in the Insulin Receptor Affects Insulin-Induced Dephosphorylation of Focal Adhesion Kinase but Leaves Other Responses Intact
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- 作者：Gerard C. M. Van der Zon ; D. Margriet Ouwens ; Jannette Dorrestijn ; and J. Antonie Maassen
- 刊名：Biochemistry
- 出版年：1996
- 出版时间：August 13, 1996
- 年：1996
- 卷：35
- 期：32
- 页码：10377 - 10382
- 全文大小：287K
- 年卷期：v.35,no.32(August 13, 1996)
- ISSN：1520-4995
文摘
The families of tyrosine and serine/threonine kinases exhibitshared clusters of conserved aminoacid residues. Some conserved residues are confined to the familyof tyrosine kinases (TKs), like Tyr atposition 1210 in the insulin receptor. Nearly all TKs have at thisposition Tyr, whereas Ser/Thr kinasesgenerally have Phe at this site. The three-dimensional structureof the insulin receptor TK domain showsTyr1210 to be located in the cleft, below bound ATP, in a region whichpotentially contributes to substratebinding. We have examined whether this specific Tyr residuecontributes to the generation of TK-specificresponses, such as Tyr phosphorylation of Shc, activation of Ras andErk1,2, and stimulation of DNAsynthesis. In addition, we have examined the contribution ofTyr1210 to insulin receptor-specific responsesas Tyr phosphorylation of IRS1, stimulation of glycogen synthesis, anddephosphorylation of focal adhesionkinase (FAK). Wild-type and a mutant insulin receptor, in whichTyr1210 was replaced by Phe, werestably expressed in CHO cells, and clones expressing similar numbers ofinsulin receptors were selected.It was found that replacement of Tyr1210 by Phe resulted in areceptor which was nearly inactive ininducing dephosphorylation of FAK. The mutant receptor was able toinduce RasGTP formation, glycogensynthesis, and activation of phosphatidylinositol 3-kinase, though themagnitude of stimulation of someresponses was decreased. These findings indicate that Tyr1210 isnot essential for the induction of tyrosinekinase-specific responses, such as activation of the Shc/Ras/Erk1,2pathway and mitogenicity. On theother hand, the abrogation of insulin-induced FAK dephosphorylationindicates that Tyr1210 is involvedin coupling of the activated receptor to some downstream targets.Thus, Tyr1210 may fine tune thesignal generated by the activated insulin receptor.