N-Myristoylation and βγ Play Roles beyond Anchorage in the Palmitoylation of the G Protein αoSubunit

• Published in: The Journal of biological chemistry Vol. 274; no. 52; p. 37435
• Main Authors: Yuren Wang, Rolf T. Windh, Catherine A. Chen, David R. Manning
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 24.12.1999
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.52.37435

Many of the α subunits of heterotrimeric GTP-binding regulatory proteins (G proteins) are palmitoylated, a modification proposed to play a key role in the stable anchorage of the subunits to the plasma membrane. Palmitoylation of α subunits from the G i family is preceded by N -myristoylation, which alone or together with βγ probably supports a reversible interaction of the α subunit with membrane as a prerequisite to the eventual incorporation of palmitate. Previous studies have not addressed, however, the question of whether membrane association alone, carried out through N -myristoylation, interaction with βγ, or other events, is sufficient for palmitoylation. We report here for α o that it is not. We found that N -myristoylation is required for palmitoylation at least in part because it supports events subsequent to membrane attachment. Mutants of α o designed to target the subunit to membrane without an N -myristoyl group are unable to be palmitoylated as evaluated by incorporation of [ 3 H]palmitate. Mutants of α o unable to interact normally with βγ yet still attach to membrane demonstrate that βγ, in contrast, is not required for palmitoylation. βγ becomes necessary, however, when the N -myristoyl group is absent. Our results suggest that N -myristoylation and βγ, while almost certainly relevant to the reversible interaction of α o with membrane, also play at least partly overlapping, post-anchorage roles in palmitoylation.