Trans-Golgi-associated GTPase that regulates protein sorting. Controls the targeting of ARL1 and its effector to the trans-Golgi. Required for the lipidation of chylomicrons in the intestine and required for VLDL lipidation in the liver. The protein encoded by this gene is a membrane-associated GTP-ase which localizes to the plasma membrane and is related to the ADP-ribosylation factor (ARF) and ARF-like (ARL) proteins. This gene plays a role in membrane trafficking between the trans-Golgi network and endosomes. Alternatively spliced transcript variants encoding different isoforms have been identified.