This gene encodes component A of the RAB geranylgeranyl
transferase holoenzyme. In the dimeric holoenzyme, this subunit
binds unprenylated Rab GTPases and then presents them to the
catalytic Rab GGTase subunit for the geranylgeranyl transfer
reaction. Rab GTPases need to be geranylgeranyled on either one or
two cysteine residues in their C-terminus to localize to the
correct intracellular membrane. Mutations in this gene are a cause
of choroideremia; also known as tapetochoroidal dystrophy (TCD).
This X-linked disease is characterized by progressive dystrophy of
the choroid, retinal pigment epithelium and retina. Alternative
splicing results in multiple transcript variants encoding different
isoforms.
