Genome organization of human 48-kDa oligosaccharyltransferase (DDOST).

The enzyme oligosaccharyltransferase (dolichyl-diphosphooligosaccharide-protein glycosyltransferase; EC 2. 4.1.119) (DDOST) catalyzes the transfer of a high-mannose oligosaccharide (GlcNac2Man9Glc3) from a dolichol-linked oligosaccharide donor (dolichol-P-GlcNac2Man9Glc3) onto the asparagine acceptor site within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains across the membrane of the endoplasmic reticulum. We isolated mouse and human DDOST cDNAs from retinoic acid-treated mouse P19 EC cells and human NT-2 cells, respectively. DDOST mRNA is expressed intensely in heart and pancreas, but at lower levels in brain. Here we show that the human DDOST 48-kDa subunit gene (HGMW-approved symbol DDOST) is organized into 11 exons expanding about 9 kb. This DDOST subunit gene is localized on chromosome 1p36.1 by fluorescence in situ hybridization analysis.