| First Author | Ramírez AS | Year | 2019 |
| Journal | Science | Volume | 366 |
| Issue | 6471 | Pages | 1372-1375 |
| PubMed ID | 31831667 | Mgi Jnum | J:319945 |
| Mgi Id | MGI:6867110 | Doi | 10.1126/science.aaz3505 |
| Citation | Ramirez AS, et al. (2019) Cryo-electron microscopy structures of human oligosaccharyltransferase complexes OST-A and OST-B. Science 366(6471):1372-1375 |
| abstractText | Oligosaccharyltransferase (OST) catalyzes the transfer of a high-mannose glycan onto secretory proteins in the endoplasmic reticulum. Mammals express two distinct OST complexes that act in a cotranslational (OST-A) or posttranslocational (OST-B) manner. Here, we present high-resolution cryo-electron microscopy structures of human OST-A and OST-B. Although they have similar overall architectures, structural differences in the catalytic subunits STT3A and STT3B facilitate contacts to distinct OST subunits, DC2 in OST-A and MAGT1 in OST-B. In OST-A, interactions with TMEM258 and STT3A allow ribophorin-I to form a four-helix bundle that can bind to a translating ribosome, whereas the equivalent region is disordered in OST-B. We observed an acceptor peptide and dolichylphosphate bound to STT3B, but only dolichylphosphate in STT3A, suggesting distinct affinities of the two OST complexes for protein substrates. |
