| Modification Notes |
Rab 3, a neural/neuroendocrine-specific member of the Rab family, is involved in Ca2+-regulated exocytosis. Rab 3 functions in an inhibitory capacity by controlling the recruitment of secretory vesicles into a releasable pool at the plasma membrane. Rim (Rab 3 interacting molecule), a putative effector protein for Rab 3 proteins, is thought to regulate neutrotransmitter release through its interaction with Rab 3 and other synaptic proteins. The mammalian genome contains four Rim genes that encode six forms of Rim: Rim1å, 2å, 2∫, 2©, 3© and 4©. Rim1å and 2å are composed of an N-terminal zinc finger, which contains the Rab 3 binding site, a central PDZ domain and two C-terminal C2 domains. Rim2∫ is nearly identical to Rim2å, with the exception of an N-terminal zinc-finger region which Rim2∫ lacks. Rim2©, 3© and 4© lack the N-terminal zinc finger and PDZ domain, and consist of only the C-terminal C2 domain with neighboring sequences. Rim4 (Rab 3 interacting molecule 4), also known as Rim4© or regulating synaptic membrane exocytosis protein 4, is a 269 amino acid protein that localizes to the cell junction and regulates synaptic membrane exocytosis. |