Overview of the posttranslational modifications of Ras proteins in cells.

FTase or GGTase I transfers a farnesyl (F) group or a geranylgeranyl group from FPP or GGPP to the thiol group of the cysteine residue in the CAAX motif. The C-terminal tripeptide is removed by a CAAX-specific endoprotease in the endoplasmatic reticulum. A PPMTase attaches the methyl group from S-adenosylmethionine (SAM) to the C-terminal cysteine. Finally, a prenyl protein–specific palmitoyltransferase (PPPTase) attaches palmitoyl groups (P) to cysteines near the farnesylated C-terminus. PPMTI indicates prenyl protein–specific methyltransferase inhibitor.