Vesicle-associated membrane protein-associated protein B/C is a protein that in humans is encoded by the VAPB gene.[5][6] The VAPB gene is found on the 20th human chromosome. Together with VAPA, it forms the VAP protein family.
The protein encoded by this gene is a type IV membrane protein found in plasma and intracellular vesicle membranes. The encoded protein is found as a homodimer and as a heterodimer with VAPA. This protein also can interact with VAMP1 and VAMP2 and may be involved in vesicle trafficking.[6]
Like VAPA, VAPB binds to proteins that contain a FFAT motif.[7] Considerable interest in VAPB has arisen because mutations in this protein are associated with rare, familial forms of motor neuron disease (also called amyotrophic lateral sclerosis and Lou Gehrig's disease).[8]