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Rab GTPase family 15 (Rab15) Rab15 colocalizes with the transferrin receptor in early endosome compartments, but not with late endosomal markers. It codistributes with Rab4 and Rab5 on early/sorting endosomes, and with Rab11 on pericentriolar recycling endosomes. It is believed to function as an inhibitory GTPase that regulates distinct steps in early endocytic trafficking. GTPase activating proteins (GAPs) interact with GTP-bound Rab and accelerate the hydrolysis of GTP to GDP. Guanine nucleotide exchange factors (GEFs) interact with GDP-bound Rabs to promote the formation of the GTP-bound state. Rabs are further regulated by guanine nucleotide dissociation inhibitors (GDIs), which facilitate Rab recycling by masking C-terminal lipid binding and promoting cytosolic localization. Most Rab GTPases contain a lipid modification site at the C-terminus, with sequence motifs CC, CXC, or CCX. Lipid binding is essential for membrane attachment, a key feature of most Rab proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",