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 .