title: Guanine nucleotide-binding protein in sea urchin eggs serving as the specific substrate of islet-activating protein, pertussis toxin.
abstract: A GTP-binding protein serving as the specific substrate of islet-activating protein (IAP), pertussis toxin, was partially purified from Lubrol extract of sea urchin egg membranes. The partially purified protein possessed two polypeptides of 39 and 37 kDa; the 39 kDa polypeptide was specifically ADP-ribosylated by IAP and the 37 kDa protein cross-reacted with the antibody prepared against purified beta gamma-subunits of alpha beta gamma-heterotrimeric IAP substrates from rat brain. Incubation of this sea urchin IAP substrate with a non-hydrolyzable GTP analogue resulted in a reduction of the apparent molecular mass on a column of gel filtration as had been the case with purified rat brain IAP substrates, suggesting that the sea urchin IAP substrate was also a heterooligomer dissociable into two polypeptides in the presence of GTP analogues. Thus, the 39 and 37 kDa polypeptides of the sea urchin IAP substrate correspond to the alpha- and beta-subunits, respectively, of mammalian IAP substrates which are involved in the coupling between membrane receptor and effector systems.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D003429:Cross Reactions; D019204:GTP-Binding Proteins / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D010063:Ovum / Q000032:analysis; D037342:Pertussis Toxin; D012617:Sea Urchins; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
chemical_list: D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D008274:Magnesium