Identification and purification of a novel G protein from neutrophils.
A novel G protein which appears to couple chemotactic peptide receptors to a polyphosphoinositide phospholipase C has been purified from rabbit neutrophils. Neutrophil membranes were solubilized with sodium cholate and fractionated by successive anion exchange, gel filtration and hydrophobic chromatography. Guanosine-5'-(3-O-thio)triphosphate binding activity was purified 170-fold from the soluble extract. The alpha-subunit of the purified G protein was identified by pertussis toxin-catalyzed ADP-ribosylation, and found to have an Mr of 40,000. The beta-subunit (Mr 36,000) comigrated on SDS-polyacrylamide gel electrophoresis with the beta-subunits of bovine brain Gi and Go. The neutrophil pertussis toxin substrate is highly unstable in cholate solution unless 30% ethylene glycol is added. Structural and functional analysis of this novel G protein will advance our understanding of the molecular mechanisms of coupling of receptors to phospholipase C.
D000818:Animals; D019204:GTP-Binding Proteins / Q000097:blood* / Q000302:isolation & purification; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000097:blood; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D009504:Neutrophils / Q000378:metabolism*; D011485:Protein Binding; D011817:Rabbits; D013873:Thionucleotides / Q000097:blood
D046911:Macromolecular Substances; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins