A novel N-terminal motif for palmitoylation of G-protein α subunits

• Published in: Biochemical journal 1993-04, Vol.291 (2), p.349-353
• Main Authors: PARENTI, M, VIGANO, M. A, NEWMAN, C. M. H, MILLIGAN, G, MAGEE, A. I
• Format: Article
• Language: English
• Subjects: Acylation; Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Cell Line; DNA - genetics; Fundamental and applied biological sciences. Psychology; GTP-Binding Proteins - genetics; GTP-Binding Proteins - metabolism; Hybrid Cells; Immunosorbent Techniques; Mice; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Myristic Acid; Myristic Acids - metabolism; Palmitic Acid; Palmitic Acids - metabolism; PC12 Cells; Protein Processing, Post-Translational; Rats; Transfection; Translation. Translation factors. Protein processing
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2910349

We have examined the post-translational processing of G alpha subunits expressed endogenously in rat PC12 and NG108-15 rat/mouse hybrid cells, and after transfection of cDNA expression constructs into COS cells. Thioester-linked palmitoylation of alpha o, alpha s, alpha q/alpha 11 and alpha 12 has been detected by metabolic labelling with [3H]palmitate and immunoprecipitation. Palmitoylation of alpha o occurs post-translationally in cells treated with protein-synthesis inhibitors, suggesting possible dynamic acylation. Palmitoylation of the C-terminal CAAX motif has been excluded. Site-directed mutagenesis of alpha o has been used to implicate the site of modification as a cysteine residue next to the N-terminal myristoylated glycine, in a novel protein-lipid modification motif Met-Gly-Cys. The non-palmitoylated alpha o mutant is still myristoylated but shows reduced membrane binding, suggesting that reversible palmitoylation may regulate G alpha localization and function.