Melanie McDowell

Thanks Alexej!

Thank you to all the generations of postdocs in the Sinning lab who contributed to this project and to our collaborators in the Strahl and Robinson labs! Lots of exciting new insights into Pmt4 biology together with this paper from the Li group last month (doi.org/10.1038/s414...).

The last chapter from my postdoc days is finally online! We solve structures of the ER membrane O-mannosyltransferase Pmt4 and uncover a functionally important cytosolic binding site for the Dol-P-Man substrate lipid - allosteric regulation or a long sought after Dol-P-Man flippase?? 🔄 rdcu.be/eUJfb

Thanks André!

Thanks :)

Thank you!!

Thanks Ünal! Hope all is well and hello from Frankfurt

Thank you, still some surprises left :)

Thanks!

Thanks Alexej and for your input!

Our first lab paper is out! We identify and solve the first structure of the SND3 translocon involved in fungal membrane protein insertion. Congratulations @tzujingyang.bsky.social, and our colleagues @saumyakm.bsky.social, @hummerlab.bsky.social and Julian Langer. Read more ⬇️ and ➡️ rdcu.be/eNgIO

Global analysis of translocon remodeling during protein synthesis at the ER - Nature Structural & Molecular Biology The authors use selective ribosome profiling to define how and when factors for N-glycosylation and membrane insertion engage and disengage from the core Sec61 translocation channel during biogenesis ...

This was a fun new collaboration using selective ribosome profiling to understand how the subunit composition of the ER translocon is tailored by the nascent chain. Congratulations to everyone involved!

www.nature.com/articles/s41...

Great session with Melanie McDowell today!
She shared exciting insights into how proteins find their way into the ER.

#imprs #imprs_cbp #phd #gradschool #biophysics

Out today in @nature.com: Together with the Honigmann, Shevchenko, Drobot and Hof labs, we present a general workflow for imaging the localization and transport of individual lipids in cells and mapping their metabolism.
www.nature.com/articles/s41...

Structural basis of an EMC:Spf1 insertase-dislocase complex in the eukaryotic endoplasmic reticulum Most eukaryotic membrane proteins are inserted into the membrane at the endoplasmic reticulum (ER). This essential but error-prone process relies on molecular quality control machineries to prevent mi...

Super excited to share our new #preprint on #BioRxiv ✨
We reveal the structural basis of a partnership between the ER membrane complex (EMC) and the P5A-ATPase Spf1 — an insertase–dislocase duo that coordinates membrane protein biogenesis and quality control.
www.biorxiv.org/content/10.1...

The EMC acts as a chaperone for membrane proteins - Nature Communications Membrane proteins are essential for any cell but difficult to fold. Here, the authors show that the EMC acts as a chaperone for membrane proteins. They dissect client recognition and provide a molecul...

Excited to share our latest study in @natcomms.nature.com , where we characterize the chaperone function of the ER membrane protein complex (EMC)—supporting membrane protein biogenesis beyond insertion!
1/9

www.nature.com/articles/s41...

The power of Chaetomium 🧫🏋‍♂️ super happy for the collaboration on this project! Congratulations to @ahmed-noor-agip.bsky.social, @pamornelas.bsky.social and all co-authors 🙌🏻

Flyer SFB1381 Symposium March 23-25, 2026

Mark your calendars:
Our 2nd International Symposium on "Dynamic Organization of Cellular Protein Machineries" takes place from March 23-25 2026 in Freiburg. We have an amazing line-up of external and internal speakers and look forward to exciting presentations and discussions!

@uni-freiburg.de

Thanks Alexej! Indeed the puzzle pieces are fitting into place...so similar yet different at the same time.

Thanks Tomáš! Indeed I also think that's an exciting avenue.

Thank you! Indeed that seems to be the case in Chaetomium at least.

Many thanks to our colleagues @mpibp.bsky.social, @saumyakm.bsky.social, @hummerlab.bsky.social and Julian Langer, for their fantastic collaboration on this story!

Excitingly, we find that the SND3 translocon has an analogous organisation to the metazoan multipass translocon, indicating that fungi and other eukaryotic taxa have evolved a distinct, reduced-complexity machinery for the insertion of multipass membrane proteins.

Indeed, molecular dynamics simulations show that SND3 disrupts the lipid bilayer and promotes lipid scrambling via its membrane-embedded hydrophilic groove, suggesting that SND3 is a membrane insertase with a novel fold.

Within this Snd3 translocon complex, CCDC47 and the SEC61β N-terminus keep the SEC61 translocon ‘out of action’, indicating that substrate insertion proceeds via another route.

We reveal the cellular context of the SND3 component of the fungal SND pathway, showing it forms an intramembrane complex with CCDC47, the SEC61 translocon and TRAPɑ beneath the ribosome tunnel exit.

Proud to share our first lab pre-print: “SND3 is the membrane insertase within a fungal multipass translocon” where @tzujingyang.bsky.social solved the structure of a ribosome-associated SND3-translocon complex involved in ER membrane protein insertion ➡️ doi.org/10.1101/2025...

Substrate-induced assembly and functional mechanism of the bacterial membrane protein insertase SecYEG-YidC The universally conserved Sec translocon and the YidC/Oxa1-type insertases mediate biogenesis of alpha-helical membrane proteins, but the molecular basis of their cooperation has remained disputed over decades. A recent discovery of a multi-subunit insertase in eukaryotes has raised the question about the architecture of the putative bacterial ortholog SecYEG-YidC and its functional mechanism. Here, we combine cryogenic electron microscopy with cell-free protein synthesis in nanodiscs to visualize biogenesis of the polytopic membrane protein NuoK, the subunit K of NADH-quinone oxidoreductase, that requires both SecYEG and YidC for insertion. We demonstrate that YidC is recruited to the back of the translocon at the late stage of the substrate insertion, in resemblance to the eukaryotic system, and in vivo experiments indicate that the complex assembly is vital for the cells. The nascent chain does not utilize the lateral gate of SecYEG, but enters the lipid membrane at the SecYE-YidC interface, with YidC being the primary insertase. SecYEG-YidC complex promotes folding of the nascent helices at the interface prior their insertion, so the examined cellular pathway follows the fundamental thermodynamic principles of membrane protein folding. Our data provide the first detailed insight on the elusive insertase machinery in the physiologically relevant environment, highlight the importance of the nascent chain for its assembly, and prove the evolutionary conservation of the gate-independent insertion route. ### Competing Interest Statement The authors have declared no competing interest. Deutsche Forschungsgemeinschaft, https://ror.org/018mejw64, Ke1879/3, 267205415 (CRC 1208) European Research Council, https://ror.org/0472cxd90, CRYOTRANSLATION

Very special feelings to announce this one... A project that started like 10 years ago is reaching the finish line, ready to shine. In a dream-team with @beckmannlab.bsky.social we solved the long-chased structure of the active membrane protein insertase SecYEG-YidC
www.biorxiv.org/content/10.1...

🎉 We’re absolutely thrilled: SCALE has been selected as a DFG Excellence Cluster!
A huge thank you to our incredible team—this would not have been possible without your dedication and talent. 🙌 @dfg.de
#ClustersOfExcellence #SCALEcluster 🧵

Thank you so much for guiding me on this amazing journey, @poulnissen.bsky.social, @charlottstock.bsky.social, and @tdieudonne.bsky.social. So great and thorough discussion with @melaniemcdowell.bsky.social, @henrietteautzen.bsky.social and Daan van Aalten. I highly appreciate your involvement.