BAP31 (B-cell receptor-association protein 31) is a transmembrane protein associated with the endplasmic reticulum (ER) and ER-Golgi intermediates and has been implicated in protein trafficking and apoptosis. During apoptosis Bap31 is cleaved by caspase-8 at two carboxy-terminal sites which can then direct apoptotic signals between the ER and mitochondria. Association of BAP31 with the anti-apoptotic proteins Bcl-2 or Bcl-xL could function to regulate this ER-mitochondrial pathway. Several studies have shown that BAP31 can control the trafficking of select proteins between the ER and Golgi apparatus and can affect the transport of proteins to the cell surface.
