Rab effector involved in protein trafficking from apical recycling endosomes to the apical plasma membrane. Involved in insulin granule exocytosis. May regulate V-ATPase intracellular transport in response to extracellular acidosis. Interacts with RAB11FIP4 (By similarity). Interacts with NAPG (By similarity). Interacts with RO60 (By similarity). Interacts with RAB11A that has been activated by GTP binding (By similarity). Binds to vesicles enriched in neutral phospholipids via its C2 domain. The interaction is favored by Mg(2+) rather than Ca(2+) (By similarity). Phosphorylated on serine and threonine residues. Phosphorylation at Ser-357 is PKA-dependent.