Description
This enzyme, along with protein farnesyltransferase (EC 2.5.1.58) and protein geranylgeranyltransferase type II (EC 2.5.1.60), constitutes the protein prenyltransferase family of enzymes. Catalyses the formation of a thioether linkage between the C-1 atom of the geranylgeranyl group and a cysteine residue fourth from the C-terminus of the protein. These protein acceptors have the C-terminal sequence CA1A2X, where the terminal residue, X, is preferably leucine; serine, methionine, alanine or glutamine makes the protein a substrate for EC 2.5.1.58. The enzymes are relaxed in specificity for A1, but cannot act if A2 is aromatic. Known targets of this enzyme include most γ-subunits of heterotrimeric G proteins and Ras-related GTPases such as members of the Ras and Rac/Rho families. A zinc metalloenzyme. The Zn2+ is required for peptide, but not for isoprenoid, substrate binding.