May act as a GTPase-activating protein for Rab family protein(s) (PubMed:20727515). Involved in neuronal projections development, probably through a negative modulation of ARF6 function (PubMed:20727515). Involved in the regulation of synaptic vesicle trafficking (By similarity). Interacts with ARF6. Mainly cytoplasmatic with partial expression at the plasma membrane (By similarity). Associates with certain types of membrane phosphoinositides, preferentially those phosphorylated at the D5 position of the inositol ring such as phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3) (By similarity). Expressed in brain, particularly at the level of the cortex and the hippocampus. Expressed in the inner ear in spiral ganglion cells, a collection of neurons critical for hearing and balance. The Rab-GAP TBC domain is essential for phosphatidylinositol binding.