TBC1 Domain Family, Member 3B (TBC1D3B)

PRC17 shares 84% amino acid identity with TRE2 (USP6), but it lacks the ubiquitin hydrolase domain found in TRE2. Northern blot analysis and quantitative RT-PCR detected a low level of expression in all tissues examined. All TBC1D3 paralogs encode a deduced 549-amino acid protein, but missense changes at 6 residues among the paralogs result in 5 different TBC1D3 isoforms. The TBC1D3 paralogs appeared to be differentially expressed in human tissues.When overexpressed in a mouse fibroblast cell line, PRC17 induced growth in low serum and loss of contact inhibition. PRC17 was also tumorigenic in nude mice. PRC17 interacted directly with RAB5 and stimulated its GTP hydrolysis. Point mutations that altered conserved amino acids within the PRC17 GAP domain abolished its transforming ability.