| Abstract: |
The Src family consists of nine related tyrosine protein kinases with a common domain structure, including a myristylated N-terminal glycine residue. In this report, we identify cysteine residues within the N-terminal region of the Src family member Fyn which serve as sites for palmitylation. To facilitate detection of protein fatty acylation, p59(fyn) was overexpressed in COS cells and incubated with radioiodinated fatty acid analogs of myristate (IC13) or palmitate (IC16). Incorporation of both fatty acids into p59(fyn) was readily observed. Acylation with the palmitate analog was prevented when Gly-2 was mutated to alanine, implying that N-myristylation is required for palmitylation, and when either Cys-3 or Cys-6 was mutated to serine. Palmitylation was shown to alter the distribution of p59(fyn) between membrane-bound and soluble fractions. In contrast, no incorporation of the palmitate analog into pp60(v-src), which lacks N-terminal cysteine residues, was observed. Mutation of Ser-3 of Src to cysteine, but not Ser-6, resulted in incorporation of the palmitate analog. These results serve to delineate sequence elements important for dual acylation of proteins, and further illustrate the utility of radioiodinated fatty acid analogs for studies of protein fatty acid acylation. |
| Keywords: |
gene mutation; proto-oncogene proteins; nonhuman; comparative study; protein domain; animal; protein protein interaction; cell line; transfection; protein tyrosine kinase; cercopithecus aethiops; kidney; amino acid sequence; molecular sequence data; protein processing, post-translational; amino terminal sequence; iodine radioisotopes; cellular distribution; plasmids; mutagenesis, site-directed; binding sites; protein structure; sequence homology; subcellular fractions; membrane binding; multigene family; tritium; acylation; myristic acid; restriction mapping; palmitic acid; palmitic acids; protein-tyrosine kinase; myristic acids; human; priority journal; article; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; genes, src
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