The function of ENSG00000134594 (RAB33A, RAB33A, member RAS oncogene family) is as follows. The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes (By similarity). Rabs cycle between an inactive GDP-bound form and an active GTP-bound form that is able to recruit to membranes different sets of downstream effectors directly responsible for vesicle formation, movement, tethering and fusion (By similarity). Modulates autophagosome formation through interaction with ATG16L1 (By similarity). {ECO:0000250|UniProtKB:P97950, ECO:0000250|UniProtKB:Q9H082}.