The Six Amino-Terminal Amino Acids of p60^src Are Sufficient To Cause Myristylation of p21^v-ras

Abstract

We have used oligonucleotide-directed mutagenesis to replace the N-terminal amino acids of p21^v-ras with residues which mimic the amino terminus of p60^v-src. p21^v-ras protein possessing only the first five amino acids of p60^src was not myristylated, while substitution of residue 6 (serine) produced a protein p21(GSSKS) which incorporated [³H]myristic acid that was stable to hydroxylamine, sensitive to inhibitors of protein synthesis, and found in both the normally nonacylated precursor and mature forms of p21(GSSKS). This defines the minimum framework of the p60^v-src myristylation signal (glycine 2 and serine 6) and identifies serine 6 as a crucial part of that signal for myristylation of a protein in vivo.