Download MendeleyAn ER translocon for multi-pass membrane protein biogenesis.
McGilvray, P.T., Anghel, S.A., Sundaram, A., Zhong, F., Trnka, M.J., Fuller, J.R., Hu, H., Burlingame, A.L., Keenan, R.J.(2020) Elife 9
- PubMed: 32820719
- DOI: https://doi.org/10.7554/eLife.56889
- Primary Citation of Related Structures:
6W6L - PubMed Abstract:
Membrane proteins with multiple transmembrane domains play critical roles in cell physiology, but little is known about the machinery coordinating their biogenesis at the endoplasmic reticulum. Here we describe a ~ 360 kDa ribosome-associated complex comprising the core Sec61 channel and five accessory factors: TMCO1, CCDC47 and the Nicalin-TMEM147-NOMO complex. Cryo-electron microscopy reveals a large assembly at the ribosome exit tunnel organized around a central membrane cavity. Similar to protein-conducting channels that facilitate movement of transmembrane segments, cytosolic and luminal funnels in TMCO1 and TMEM147, respectively, suggest routes into the central membrane cavity. High-throughput mRNA sequencing shows selective translocon engagement with hundreds of different multi-pass membrane proteins. Consistent with a role in multi-pass membrane protein biogenesis, cells lacking different accessory components show reduced levels of one such client, the glutamate transporter EAAT1. These results identify a new human translocon and provide a molecular framework for understanding its role in multi-pass membrane protein biogenesis.
Organizational Affiliation:
Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, United States.
