Endoplasmic reticulum (ER)-anchored protein that mediates the formation of contact sites between the ER and endosomes via interaction with FFAT motif-containing proteins such as STARD3 or WDR44. STARD3-VAPA interaction enables cholesterol transfer from the ER to endosomes. Via interaction with WDR44 participates in neosynthesized protein export. In addition, recruited to the plasma membrane through OSBPL3 binding. The OSBPL3-VAPA complex stimulates RRAS signaling which in turn attenuates integrin beta-1 (ITGB1) activation at the cell surface. With OSBPL3, may regulate ER morphology. May play a role in vesicle trafficking.
Subcellular locations: Endoplasmic reticulum membrane, Cell membrane, Cell junction, Tight junction, Nucleus membrane
Present in the plasma membrane and in intracellular vesicles, together with SNARE proteins. May also associate with the cytoskeleton. Colocalizes with OCLN at the tight junction in polarized epithelial cells.