Geranylgeranyl transferase type-2 subunit beta (IPR026873)

Short name: Ptb1

Overlapping homologous superfamilies

Family relationships



This entry includes the beta subunit of geranylgeranyl transferase type-2 (GGTase-II), which is also known as Rab geranyl-geranyltransferase subunit beta, Bet2 and Ptb1. GGTase-II catalyses the transfer of a geranyl-geranyl moiety from geranyl-geranyl pyrophosphate to proteins having the C-terminal -XCC or -XCXC [PMID: 11675392, PMID: 8740421, PMID: 8232542]. GGTase-IIs are a subgroup of protein prenyltransferases (PTases) of lipid-modifying enzymes. PTases 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-II). GGTase-II catalyzes alkylation of both cysteine residues in Rab proteins containing carboxy-terminal "CC", "CXCX" or "CXC" motifs. PTases are heterodimeric with both alpha and beta subunits required for catalytic activity. The beta subunit has an alpha 6 - alpha 6 barrel fold. In contrast to other prenyltransferases, GGTas-II requires an escort protein to bring the substrate protein to the catalytic heterodimer and to escort the geryanylgeranylated product to the membrane [PMID: 12022885, PMID: 9109664].

GO terms

Biological Process

GO:0018344 protein geranylgeranylation

Molecular Function

GO:0004663 Rab geranylgeranyltransferase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.