RAB31, Member RAS Oncogene Family (RAB31)

RAB31 showed low steady-state GTPase activity in the absence of a GTPase-activating protein. However, in contrast to most small GTPases, mutation of a conserved glutamine (Q64) to leucine in the GTP-binding motif of RAB31 did not inhibit its GTPase activity. Similar results were observed following mutation of the conserved glutamine in RAB32 and RAB11A, suggesting that these proteins form a subfamily of small GTPases.The deduced 194-amino acid RAB31 protein, which the authors referred to as RAB22B, appeared to be an isoform of the human homolog of canine Rab22. Northern blot analysis detected a major transcript of 4.0 kb in all tissues tested and a minor transcript of 1.0 kb in tissues with relatively high expression, such as testis, ovary, lung, and leukocytes.