The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes. Rabs cycle between active GTP-bound and inactive GDP-bound states (PubMed:28930687). In their active state, drive transport of vesicular carriers from donor organelles to acceptor organelles to regulate the membrane traffic that maintains organelle identity and morphology (PubMed:28930687). Regulates the compacted morphology of the Golgi (By similarity). Promotes cytosolic DNA-induced innate immune responses. Regulates IFN responses against DNA viruses by regulating the CGAS-STING signaling axis (PubMed:28930687). GTP + H2O = GDP + H(+) + phosphate Regulated by guanine nucleotide exchange factors (GEFs) which promote the exchange of bound GDP for free GTP, GTPase activating proteins (GAPs) which increase the GTP hydrolysis activity, and GDP dissociation inhibitors which inhibit the dissociation of the nucleotide from the GTPase. Interacts (in GTP-bound form) with GARIN4 (via N-terminus) (By similarity). Interacts (in GTP-bound form) with GARIN5A (PubMed:28930687). Interacts (in GTP-bound form) with GARIN1B (PubMed:34714330). Localized in the Golgi apparatus in the round spermatids and in the acrosome in the elongating spermatid. Belongs to the small GTPase superfamily. Rab family.