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FYVE-related domain found in rabphilin-3A and similar proteins Rabphilin-3A, also termed exophilin-1, is an effector protein that binds to the GTP-bound form of Rab3A, which is one of the most abundant Rab proteins in neurons and predominantly localized to synaptic vesicles. Rabphilin-3A is homologous to alpha-Rab3-interacting molecules (RIMs). It is a multi-domain protein containing an N-terminal Rab3A effector domain, a proline-rich linker region, and two tandem C2 domains. The effector domain binds specifically to the activated GTP-bound state of Rab3A and harbors a conserved FYVE zinc finger. The C2 domains are responsible for the binding of phosphatidylinositol-4,5-bisphosphate (PIP2) , a key player in the neurotransmitter release process. Thus, Rabphilin-3A has also been implicated in vesicle trafficking. The FYVE domain of Rabphilin-3A resembles a FYVE-related domain that is structurally similar to the canonical FYVE domains but lacks the three signature sequences: an N-terminal WxxD motif (x for any residue), the central basic R(R/K)HHCRxCG patch, and a C-terminal RVC motif.
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