Rab3interacting

Rab3interacting is a descriptor used in molecular biology to refer to proteins that bind the Rab3 family of small GTPases and influence vesicular trafficking, particularly in secretory pathways. The term most often appears in reference to the Rab3-interacting molecule family, abbreviated as RIM, which includes proteins such as RIM1 and RIM2.

RIM proteins are presynaptic scaffolding components that organize the active zone where neurotransmitter release occurs. They help couple the arrival of calcium signals to the exocytosis machinery and contribute to vesicle priming, thereby regulating release probability. RIM proteins interact with Rab3 on synaptic vesicles, with Munc13 to promote priming, and with voltage-gated calcium channels to coordinate calcium influx with vesicle fusion. Their domain structure typically includes PDZ and C2 domains that mediate multiple protein–protein and protein–lipid interactions, and alternative splicing yields multiple isoforms with potentially distinct localization and functions.

Genes encoding RIM1 and RIM2 are expressed predominantly in neurons, with higher levels in presynaptic terminals. Isoforms such as RIM1α, RIM1β, RIM2α, and RIM2β arise from alternative promoter usage and splicing, contributing to tissue- and synapse-specific roles. The functional importance of RIM proteins is reflected in synaptic transmission and plasticity: disruption of RIM–Rab3 interactions or RIM’s scaffolding capabilities can impair neurotransmitter release and alter synaptic efficiency.

Beyond the RIM subfamily, other Rab3-interacting proteins exist, including Rab3IP (Rab3-interacting protein), which can modulate Rab3 activity or localization in various cell types. In sum, Rab3interacting proteins form a network that links Rab3 vesicles to the release machinery, with diverse roles across tissues and synapses.