Transmembrane but not soluble helices fold inside the ribosome tunnel

Manuel Bañó-Polo, Carlos Baeza-Delgado, Silvia Tamborero, Anthony Hazel, Brayan Grau, Ing Marie Nilsson, Paul Whitley, James C. Gumbart, Gunnar von Heijne, Ismael Mingarro

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26 Citations (SciVal)


Integral membrane proteins are assembled into the ER membrane via a continuous ribosome-translocon channel. The hydrophobicity and thickness of the core of the membrane bilayer leads to the expectation that transmembrane (TM) segments minimize the cost of harbouring polar polypeptide backbones by adopting a regular pattern of hydrogen bonds to form α-helices before integration. Co-translational folding of nascent chains into an α-helical conformation in the ribosomal tunnel has been demonstrated previously, but the features governing this folding are not well understood. In particular, little is known about what features influence the propensity to acquire α-helical structure in the ribosome. Using in vitro translation of truncated nascent chains trapped within the ribosome tunnel and molecular dynamics simulations, we show that folding in the ribosome is attained for TM helices but not for soluble helices, presumably facilitating SRP (signal recognition particle) recognition and/or a favourable conformation for membrane integration upon translocon entry.

Original languageEnglish
Article number5246
JournalNature Communications
Issue number1
Publication statusPublished - 7 Dec 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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