Some proteins undergo posttranslational modification by the addition of an isoprenyl lipid
(farnesyl-or geranylgeranyl-isoprenoid) to a cysteine residue proximal to the C terminus.
Protein isoprenylation promotes membrane association and contributes to protein-protein
interactions. Farnesylated proteins include small GTPases, tyrosine phosphatases, nuclear
lamina, cochaperones, and centromere-associated proteins. Prenylation is required for the
transforming activity of Ras. Because of the high frequency of Ras mutations in cancer …