RAB32, Member RAS Oncogene Family (RAB32)

The deduced 225-amino acid protein has a calculated molecular mass of 25 kD. RAB32 has an unusual GTP-binding sequence, DIAGQE, in place of the more common DTAGQE. Northern blot analysis detected a 1.35-kb RAB32 transcript in most tissues examined, with highest expression in heart, liver, and kidney. A 2.0-kb transcript was also detected in some preparations of HEL human erythroleukemia cells. Western blot analysis of human platelets showed that RAB32 had an apparent molecular mass of 28 kD, and a weak signal at 52 kD was also detected. Differential centrifugation of human platelets showed enrichment of RAB32 in the granule/mitochondrion and membrane fractions.The deduced protein contains an N-terminal nucleotide-binding domain, a central GTPase domain, and 2 C-terminal cysteines for lipid modification.