Rab3 proteins are involved in regulated exocytosis of neurotransmitters and hormones. Rab 3 GAP p130, also known as Rab3 GTPase-activating protein catalytic subunit, is a 981 amino acid protein that belongs to the Rab3-GAP catalytic subunit family. Rab 3 GAP p130 converts active RAB3-GTP to the inactive form RAB3-GDP, and is required for normal eye and brain development. Defects in Rab 3 GAP p130 are the cause of Warburg micro syndrome 1 (WARBM1). WARBM1 is a severe autosomal recessive disorder characterized by developmental abnormalities of the eye and central nervous system and by microgenitalia. The Rab 3 GAP p130 protein may participate in neurodevelopmental processes such as proliferation, migration and differentiation before synapse formation, and non-synaptic vesicular release of neurotransmitters. Existing as two alternatively spliced isoforms, the Rab 3 GAP p130 gene is conserved in chimpanzee, dog, cow, mouse, chicken, zebrafish and fruit fly, and maps to human chromosome 2q21.3.