Oligosaccharyltransferase directly binds to ribosome at a location near the translocon-binding site.
Oligosaccharyltransferase (OT) transfers high mannose-type glycans to the nascent polypeptides that are translated by the membrane-bound ribosome and translocated into the lumen of the endoplasmic reticulum through the Sec61 translocon complex. In this article, we show that purified ribosomes and OT can form a binary complex with a stoichiometry of approximately 1 to 1 in the presence of detergent. We present evidence that OT may bind to the large ribosomal subunit near the site where nascent polypeptides exit. We further show that OT and the Sec61 complex can simultaneously bind to ribosomes in vitro. Based on existing data and our findings, we propose that cotranslational translocation and N-glycosylation of nascent polypeptides are mediated by a ternary supramolecular complex consisting of OT, the Sec61 complex, and ribosomes.
Harada
Yoichiro
Y
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.
Li
Hua
H
Li
Huilin
H
Lennarz
William J
WJ
D001665:Binding Sites; D055162:Biocatalysis; D001692:Biological Transport; D006602:Hexosyltransferases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D026901:Membrane Transport Proteins; D008854:Microscopy, Electron; D011485:Protein Binding; D012270:Ribosomes / Q000378:metabolism* / Q000648:ultrastructure; D000069816:SEC Translocation Channels; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; C499383:SEC61 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase