Besides its role in detoxification of substrates by UDP glucuronyl
transferases, the preparation of antigens to be
presented on the cell surface by major histocompatibility
complex and its capacity to synthesize lipids, the ER is
responsible for the synthesis and translocation of proteins,
and the release of properly processed, folded and assembled
proteins to allow transport to their destinations. These
functions of the ER are mainly performed by three sets of
proteins: