Structural basis for coupling protein transport and N-glycosylation at the mammalian endoplasmic reticulum.
Braunger, K., Pfeffer, S., Shrimal, S., Gilmore, R., Berninghausen, O., Mandon, E.C., Becker, T., Forster, F., Beckmann, R.(2018) Science 360: 215-219
- PubMed: 29519914 
- DOI: https://doi.org/10.1126/science.aar7899
- Primary Citation of Related Structures:  
6FTG, 6FTI, 6FTJ - PubMed Abstract: 
Protein synthesis, transport, and N-glycosylation are coupled at the mammalian endoplasmic reticulum by complex formation of a ribosome, the Sec61 protein-conducting channel, and oligosaccharyltransferase (OST). Here we used different cryo-electron microscopy approaches to determine structures of native and solubilized ribosome-Sec61-OST complexes. A molecular model for the catalytic OST subunit STT3A (staurosporine and temperature sensitive 3A) revealed how it is integrated into the OST and how STT3-paralog specificity for translocon-associated OST is achieved. The OST subunit DC2 was placed at the interface between Sec61 and STT3A, where it acts as a versatile module for recruitment of STT3A-containing OST to the ribosome-Sec61 complex. This detailed structural view on the molecular architecture of the cotranslational machinery for N-glycosylation provides the basis for a mechanistic understanding of glycoprotein biogenesis at the endoplasmic reticulum.
Organizational Affiliation: 
Department of Biochemistry, Gene Center and Center for Integrated Protein Science Munich, University of Munich, 81377 Munich, Germany.