title: Intramolecular subunit interactions between insulin and insulin-like growth factor 1 alpha beta half-receptors induced by ligand and Mn/MgATP binding.
abstract: We have previously demonstrated that isolated insulin and IGF-1 alpha beta half-receptors can be reconstituted into a functional alpha 2 beta 2 hybrid receptor complex [Treadway et al. (1989) J. Biol. Chem. 264, 21450-21453]. In the present study, we have examined this assembly process by determining the effect of ligand occupancy and Mn/MgATP binding on the dimerization of mutant and wild-type insulin and IGF-1 alpha beta half-receptors. IGF-1 or Mn/MgAMPPCP binding to wild-type IGF-1 alpha beta half-receptors resulted in the specific assembly of the alpha beta half-receptors into an alpha 2 beta 2 heterotetrameric IGF-1 holoreceptor complex. Similarly, insulin binding to the kinase-deficient mutant (A/K1018) insulin alpha beta half-receptor also resulted in the specific assembly into an alpha 2 beta 2 holoreceptor complex. In contrast, Mn/MgAMPPCP treatment of A/K1018 mutant insulin alpha beta half-receptors did not induce heterotetramer assembly, consistent with the inability of this mutant receptor to bind ATP. The ability of the insulin alpha beta receptors to assemble with the IGF-1 alpha beta half-receptors was used to examine the intermolecular subunit interactions responsible for dimerization. In the presence of Mn/MgAMPPCP, the wild-type insulin and wild-type IGF-1 alpha beta half-receptors were observed to assemble into an insulin/IGF-1 alpha 2 beta 2 hybrid receptor complex. Similarly, a combination of insulin and IGF-1 induced hybrid receptor formation between wild-type IGF-1 and A/K1018 mutant insulin alpha beta half-receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology and Biophysics, University of Iowa, College of Medicine, Iowa City 52242.
authors.forename: J L
authors.initials: JL
authors.lastname: Treadway
authors.forename: A L
authors.initials: AL
authors.lastname: Frattali
authors.forename: J E
authors.initials: JE
authors.lastname: Pessin
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D002850:Chromatography, Gel; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology; D046911:Macromolecular Substances; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology; D008345:Manganese / Q000378:metabolism* / Q000494:pharmacology; D055503:Protein Multimerization; D017526:Receptor, IGF Type 1 / Q000737:chemistry* / Q000378:metabolism*; D011972:Receptor, Insulin / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D007328:Insulin; D046911:Macromolecular Substances; C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; D008345:Manganese; D007334:Insulin-Like Growth Factor I; D000255:Adenosine Triphosphate; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin; D008274:Magnesium; C002630:alpha,beta-methyleneadenosine 5'-triphosphate