An insulin receptor peptide (1135-1156) stimulates guanosine 5'-[gamma-thio]triphosphate binding to the 67 kDa G-protein associated with the insulin receptor.
Peptides representing two putative G-protein-binding motifs (GPBP1 and GPBP2) derived from insulin-receptor sequences were tested for their ability to stimulate guanosine 5'-[gamma-thio]-triphosphate (GTP[S]; 'GTP gamma S') binding to a preparation containing the 41 and 67 kDa G-proteins that are associated with the insulin receptor [Jo, Cha, Davis and McDonald (1992) Endocrinology (Baltimore) 131, 2855-2861]. GPBP2 (residues 1135-1156) specifically stimulated GTP[S] binding, whereas GPBP1 (1319-1333) did not. Substitution of Arg-1152 with Gln in GPBP2 corresponding to a mutation site in insulin-resistant patients [Cocozza, Porcellini, Riccardi, Monticelli, Condorelli, Ferrera, Pianese, Miele, Capaldo, Beguinot and Varrone (1992) Diabetes 41, 521-526] attenuated the stimulatory potency of GPBP2. Size-exclusion chromatography and studies with purified 67 kDa G-protein revealed that GPBP2 stimulated GTP[S] binding only to the 67 kDa G-protein. These studies provide evidence for a potential regulatory site for G-protein interaction with the insulin receptor in the tyrosine kinase domain.
Jo
H
H
Department of Pathology, University of Alabama, Birmingham 35294.
Radding
W
W
Anantharamaiah
G M
GM
McDonald
J M
JM
D000595:Amino Acid Sequence; D001665:Binding Sites; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D011972:Receptor, Insulin / Q000378:metabolism*
D010446:Peptide Fragments; C082834:insulin receptor peptide (1135-1156); D016244:Guanosine 5'-O-(3-Thiotriphosphate); D011972:Receptor, Insulin; D019204:GTP-Binding Proteins