ROLE OF CARBOXYLMETHYLATION IN CHEMOATTRACTANT RECEPTOR-STIMULATED G-PROTEIN ACTIVATION AND FUNCTIONAL-RESPONSES

The role of G protein gamma subunit carboxylmethylation was examined i n HL-60 granulocytes using an inhibitor of S-adenosylmethionine-depend ent methylation, periodate-oxidized adenosine (Adox). A 40-60% reducti on in gamma subunit carboxylmethylation was associated with attenuatio n of fMet-Leu-Phe-stimulated GTP gamma S binding and GTP hydrolysis, w hile plasma membrane density of formyl peptide receptors, alpha(i)2, a lpha(i)3, beta, gamma(5), and gamma(7) were not reduced. Reduced pertu ssis toxin-catalyzed ADP-ribosylation was re-established by in vitro m ethylation or addition of transducin beta gamma subunits. Superoxide r elease and inositol phosphate generation stimulated by fMet-Leu-Phe we re significantly inhibited by Adox treatment. Carboxylmethylation cont ributes to transmembrane signalling and functional responses by enhanc ing association of alpha and beta gamma subunits. (C) 1994 Academic Pr ess, Inc.