title: A new GTP-binding protein in brain tissues serving as the specific substrate of islet-activating protein, pertussis toxin.
abstract: A new GTP-binding protein serving as the specific substrate of islet-activating protein (IAP), pertussis toxin, was purified from porcine brain membranes as an alpha beta gamma-heterotrimeric structure. The alpha-subunit of the purified protein (alpha 40 beta gamma) had a molecular mass of 40 kDa and differed from that of Gi (alpha 41 beta gamma) or Go (alpha 39 beta gamma) previously purified from brain tissues. The fragmentation patterns of limited tryptic digestion and immunological cross-reactivities among the three alpha were different from one another. However, the beta gamma-subunit resolved from the three IAP substrates similarly inhibited a membrane-bound adenylate cyclase and their beta-subunits were immunologically indistinguishable from one another. Thus, the alpha 40 beta gamma is a new IAP substrate protein different from Gi or Go, in the alpha-subunit only.
mesh_terms: D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D001923:Brain Chemistry; D002462:Cell Membrane / Q000032:analysis; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D007159:Immunologic Tests; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D037342:Pertussis Toxin; D051381:Rats; D013552:Swine; D013873:Thionucleotides / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000378:metabolism*
chemical_list: D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D046911:Macromolecular Substances; D010446:Peptide Fragments; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D014357:Trypsin; D019204:GTP-Binding Proteins