| Autor: |
Philips, M R, Staud, R, Pillinger, M, Feoktistov, A, Volker, C, Stock, J B, Weissmann, G |
| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; March 1995, Vol. 92 Issue: 6 p2283-2287, 5p |
| Abstrakt: |
The gamma subunits of heterotrimeric guanine nucleotide-binding regulatory (G) proteins (G gamma) are post-translationally processed at their C termini by prenylation, proteolysis, and carboxyl methylation. Whereas prenylation of G gamma is required for membrane association of G proteins, the role of carboxyl methylation is unknown. Here we show that human neutrophils express G gamma 2 but not G gamma 3 or G gamma 7 and that carboxyl methylation of G gamma 2 is associated with signal transduction. In a reconstituted cell-free system, neutrophil G gamma 2 was labeled by the methyl donor S-[methyl-3H]adenosyl-L-methionine. Carboxyl methylation was confirmed by alkaline hydrolysis and quantitation of volatile [3H]methanol. Neutrophil G gamma 2 methylation was stimulated by activation of G protein with guanosine 5'-[beta, gamma-thio]triphosphate. We estimate that after 1 hr of G-protein activation at least 6% of the total pool of G gamma 2 was carboxyl-methylated. The inflammatory agonist fMet-Leu-Phe stimulated guanosine 5'-[beta,gamma-thio]triphosphate-dependent carboxyl methylation. Methylation of G gamma 2 was inhibited by the carboxyl methyltransferase inhibitor N-acetyl-S-trans,trans-farnesylcysteine at concentrations that affected signal transduction in neutrophils. These results demonstrate that activation of neutrophil Gi is associated with alpha-carboxyl methyl esterification of G gamma 2 and suggest that carboxyl methylation of G gamma may play a role in signal transduction. |
| Databáze: |
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