| Abstract: | Incubation of Saccharomyces cerevisiae strain JR153 with either 3H]myristate or 3H]palmitate demonstrates the synthesis of proteins that contain covalently bound fatty acids. A unique set of proteins is labeled by each fatty acid. Detailed analysis of a 20-kDa protein labeled with myristic acid demonstrates that myristate is linked to the amino-terminal glycine. We describe an enzymatic activity in yeast that will transfer myristic acid to the amino terminus of the octapeptide Gly-Asn-Ala-Ala-Ala-Ala-Arg-Arg, whose sequence was derived from a known N-myristoylated acyl protein, the catalytic subunit of cAMP-dependent protein kinase of bovine cardiac muscle. The acylation reaction is dependent on ATP and CoA, is enriched in a crude membrane fraction, and will use myristate but not palmitate as the acyl donor. Specificity of the glycyl peptide substrate is demonstrated by the observation that other glycyl peptides do not competitively inhibit myristoylation of Gly-Asn-Ala-Ala-Ala-Ala-Arg-Arg. |
