Ribophorin

Ribophorins are transmembrane glycoproteins which are located in the membrane of the rough endoplasmic reticulum, but are absent in the membrane of the smooth endoplasmic reticulum. There are two types of ribophorines: ribophorin I and II. These act in the proteic complex oligosaccharyltransferase (OST) as two different subunits of the named complex. Ribophorin I and II are only present in eukaryote cells.