<p>Rab are small GTPases implicated in vesicle trafficking, acting as molecular switches, which involves an active GTP-bound form that interacts with its target or effector protein and an inactive GDP-bound form. A subgroup of Rab effectors contain an N-terminal (70aa) Rab binding domain (RabBD). Some RabBDs have an atypical FYVE-type zinc finger inserted in the central part of the domain. For example, the structure of RabBD of Rabphilin-3A (Rab3A) consists of two long helices separated by an atypical FYVE-type zinc finger; the zinc finger does not directly interact with Rab3A. Several proteins contain a RabBD, including mammalian synaptotagmins, Noc2, Slp, Rim1 and Rim2 [<cite idref="PUB00013948"/>].</p> Rab-binding domain