Insulin activates guanosine 5'-[gamma-thio] triphosphate (GTP gamma S) binding to a novel GTP-binding protein, GIR, from human placenta.
A novel GTP-binding protein, GIR, along with insulin receptor (IR), has been partially purified from human placenta. A non-hydrolyzable substrate, GTP gamma S which is known to bind to GTP-binding proteins with high affinity, reduces insulin binding to IR-GIR fraction by approximately 29% and 100 nM insulin stimulates GTP gamma S binding to IR-GIR fraction by approximately five-fold. The molecular weight of the protein (may be subunit) that binds to 8-azido-GTP, a photoaffinity label for G-proteins, is approximately 66,000.
Srivastava
S K
SK
Department of Human Biological Chemistry & Genetics, University of Texas Medical Branch, Galveston 77550.
Singh
U S
US
D001386:Azides / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D010920:Placenta / Q000737:chemistry; D011972:Receptor, Insulin / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction
C021961:8-azidoguanosine triphosphate; D001386:Azides; D007328:Insulin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D011972:Receptor, Insulin; D019204:GTP-Binding Proteins