VAPA
Domain
The MSP domain binds the FFAT motif of many proteins.
Function
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 (PubMed:32344433, PubMed:33124732). STARD3-VAPA interaction enables cholesterol transfer from the ER to endosomes (PubMed:33124732). Via interaction with WDR44 participates in neosynthesized protein export (PubMed:32344433). In addition, recruited to the plasma membrane through OSBPL3 binding (PubMed:25447204). The OSBPL3-VAPA complex stimulates RRAS signaling which in turn attenuates integrin beta-1 (ITGB1) activation at the cell surface (PubMed:25447204). With OSBPL3, may regulate ER morphology (PubMed:16143324). May play a role in vesicle trafficking (PubMed:11511104, PubMed:19289470).
Sequence Similarities
Belongs to the VAMP-associated protein (VAP) (TC 9.B.17) family.
Tissue Specificity
Ubiquitous.
Cellular localization
- Endoplasmic reticulum membrane
- Single-pass type IV membrane protein
- Cell membrane
- Single-pass type IV membrane protein
- 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.
Alternative names
VAP33, VAPA, Vesicle-associated membrane protein-associated protein A, VAMP-A, VAMP-associated protein A, VAP-A, 33 kDa VAMP-associated protein, VAP-33