Background:  

    Small GTP-binding protein that plays a central role in regulated exocytosis and secretion. Controls the 

    recruitment, tethering and docking of secretory vesicles to the plasma membrane (By similarity). Upon 

    stimulation, switches to its active GTP-bound form, cycles to vesicles and recruits effectors such as RIMS1,

    RIMS2, Rabphilin-3A/RPH3A, RPH3AL or SYTL4 to help the docking of vesicules onto the plasma membrane 

    (By similarity). Upon GTP hydrolysis by GTPase-activating protein, dissociates from the vesicle membrane 

    allowing the exocytosis to proceed (By similarity). Stimulates insulin secretion through interaction with RIMS2 or 

    RPH3AL effectors in pancreatic beta cells (By similarity). Regulates calcium-dependent lysosome exocytosis

    and plasma membrane repair (PMR) via the interaction with 2 effectors, SYTL4 and myosin-9/MYH9 

   (PubMed:27325790). Acts as a positive regulator of acrosome content secretion in sperm cells by interacting 

   with RIMS1 (PubMed:22248876, PubMed:30599141). Plays also a role in the regulation of dopamine release by

   interacting with synaptotagmin I/SYT (By similarity).