Ribophorin II (RPN2)

RPN2 encodes a type I integral ribophorin membrane protein found only in the rough endoplasmic reticulum. The encoded protein is part of an N-oligosaccharyl transferase complex that links high mannose oligosaccharides to asparagine residues found in the Asn-X-Ser/Thr consensus motif of nascent polypeptide chains. This protein is similar in sequence to the yeast oligosaccharyl transferase subunit SWP1. The cDNA clones hybridized to mRNA species of 2.5 kb and encoded polypeptides of 68.5 and 69.3 kD, respectively. Sequence comparisons and immunoblotting with specific antibodies showed both proteins to be highly conserved throughout a variety of species. However, no relationship between the 2 proteins could be deduced from their primary sequences.