InterPro domain: IPR041960

This entry represents the beta subunit (alpha 6 - alpha 6 barrel fold) of geranylgeranyltransferase type I (GGTase-I)-like proteins containing the protein prenyltransferase (PTase) domain. GGTase-I is a subgroup of the protein prenyltransferase family of lipid-modifying enzymes PTases, which catalyze the carboxyl-terminal lipidation of Ras, Rab, and several other cellular signal transduction proteins, facilitating membrane associations and specific protein-protein interactions. Prenyltransferases employ a Zn2+ ion to alkylate a thiol group catalyzing the formation of thioether linkages between cysteine residues at or near the C terminus of protein acceptors and the C1 atom of isoprenoid lipids (geranylgeranyl (20-carbon) in the case of GGTase-I) [ 1 ]. GGTase-I prenylates the cysteine in the terminal sequence, 'CAAX' when X is Leu or Phe. Substrates for GTTase-I include the gamma subunit of neural G-proteins and several Ras-related G-proteins [ 2 , 2 ]. PTases are heterodimeric with both alpha and beta subunits required for catalytic activity.

1. Protein prenyltransferases. J. Biol. Chem. 271, 5289-92
2. Yeast protein geranylgeranyltransferase type-I: steady-state kinetics and substrate binding. Biochemistry 36, 4552-7