Vesicle Associated Membrane Protein Associated Protein B (VAPB)

VAPB 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.

Sequence analysis predicted that the 243-amino acid VAPB protein, which is 60% homologous to VAPA, contains a conserved N-terminal domain, an alpha-helical coiled-coil domain, and a C-terminal transmembrane domain. The 99-amino acid VAPC protein is a splice variant of VAPB that retains the N-terminal 70 residues but lacks the coiled-coil and transmembrane domains. Expression of VAPB was less intense than that of VAPA or the 1.9-kb VAPC transcript.