Description
This enzyme, along with protein farnesyltransferase (EC 2.5.1.58) and protein geranylgeranyltransferase type I (EC 2.5.1.59), constitutes the protein prenyltransferase family of enzymes. Attaches geranylgeranyl groups to two C-terminal cysteines in Ras-related GTPases of a single family, the Rab family (Ypt/Sec4 in lower eukaryotes) that terminate in XXCC, XCXC and CCXX motifs. Reaction is entirely dependent on the Rab substrate being bound to Rab escort protein (REP). Post-translational modification with the geranylgeranyl moiety is essential for Rab GTPases to be able to control the processes of membrane docking and fusion