The subunit structures of two distinct receptors for insulin-like growth factors I and II and their relationship to the insulin receptor.

Abstract

Intaul cells and membranes isolated from several human and rodent tissues have been affinity-crosslinked to human '261-insulin-like growth factor I (IGF-I) and '261-insulin-like growth factor I1 (IGF-11).Dodecyl sulfate-polyacryalmide gel electrophoresis of the affinity-labeled material resolves two types (type I and type I I ) of labeled membrane components that fulfill the properties expected for high affinity growth factor receptors.Type I receptors consist of three disulfidelinked forms (&& = 350,000, 320,000 and 290,000) structurally similar to the insulin receptor forms in membrane preparations from various tissues (Massague, J., Pilch, P. F., and Czech, M. P. ( 1980) h c .NutZ.A c d Sei U. S. A. 77,7137-7141).The proposed subunit stoichiometries of these type I IGF receptor forms are (p-S-S-a)-S-S-(a-S-S-b),