geranylgeranyltransferase-alpha 2 (Rab geranylgeranyltransferase alpha subunit, Rab geranylgeranyltransferase alpha subunit, Rab GG transferase alpha, Rab GGTase alpha)

Function

• alpha subunit of geranylgeranyltransferase-2
  • differs from alpha subunit of geranygeranyl transferase-1 & farnesyltransferase
• catalyzes transfer of a geranyl-geranyl moiety from geranyl-geranyl pyrophosphate to both Cys in Rab proteins with an -XXCC, -XCXC & -CCXX C-terminal, such as RAB1A, RAB3A & RAB5A respectively

geranylgeranyl diphosphate + protein-cysteine
                  <-->
S-geranylgeranyl-protein + diphosphate

Cofactor: binds 1 Zn+2 per dimer (putative)

Structure

• heterodimer of an alpha & a beta subunit, collectively called component B
• the enzymatic reaction requires the aid of a Rab escort protein (also called component A)
• belongs to the protein prenyltransferase subunit alpha family
• contains 6 PFTA repeats

Expression

• isolated from rat brain

More general terms

• protein subunit

Component of

• geranylgeranyltransferase-2 (GGTase-2, rab GGTase)

Database

• OMIM: https://mirror.omim.org/entry/601905
• UniProt: http://www.uniprot.org/uniprot/Q92696.html