9I78
Cryo-EM structure of Chaetomium thermophilum ribosome-bound SND3 translocon
This is a non-PDB format compatible entry.
Summary for 9I78
| Entry DOI | 10.2210/pdb9i78/pdb |
| EMDB information | 52656 |
| Descriptor | Translocon Sec61/SecY plug domain-containing protein, 60S ribosomal protein l5-like protein, 60S ribosomal protein L6, ... (51 entities in total) |
| Functional Keywords | membrane protein biogenesis, snd3, ribosome, co-translation translocation, insertase |
| Biological source | Thermochaetoides thermophila DSM 1495 More |
| Total number of polymer chains | 50 |
| Total formula weight | 2121454.92 |
| Authors | |
| Primary citation | Yang, T.J.,Mukherjee, S.,Langer, J.D.,Hummer, G.,McDowell, M.A. SND3 is the membrane insertase within a distinct SEC61 translocon complex. Nat Commun, 16:9566-9566, 2025 Cited by PubMed Abstract: During the biogenesis of most eukaryotic integral membrane proteins (IMPs), transmembrane domains are inserted into the endoplasmic reticulum membrane by a dedicated insertase or the SEC61 translocon. The SRP-independent (SND) pathway is the least understood route into the membrane, despite catering for a broad range of IMP types. Here, we show that Chaetomium thermophilum SND3 is a membrane insertase with an atypical fold. We further present a cryo-electron microscopy structure of a ribosome-associated SND3 translocon complex involved in co-translational IMP insertion. The structure reveals that the SND3 translocon additionally comprises the complete SEC61 translocon, CCDC47 and TRAPɑ. Here, the SEC61β N-terminus works together with CCDC47 to prevent substrate access to the translocon. Instead, molecular dynamics simulations show that SND3 disrupts the lipid bilayer to promote IMP insertion via its membrane-embedded hydrophilic groove. Structural and sequence comparisons indicate that the SND3 translocon is a distinct multipass translocon in fungi, euglenozoan parasites and other eukaryotic taxa. PubMed: 41162385DOI: 10.1038/s41467-025-65357-z PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.2 Å) |
Structure validation
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