Cotranslational folding of membrane proteins probed by arrest-peptide-mediated force measurements.

ABSTRACT: Polytopic membrane proteins are inserted cotranslationally into target membranes by ribosome-translocon complexes. It is, however, unclear when during the insertion process specific interactions between the transmembrane helices start to form. Here, we use a recently developed in vivo technique to measure pulling forces acting on transmembrane helices during their cotranslational insertion into the inner membrane of Escherichia coli to study the earliest steps of tertiary folding of five polytopic membrane proteins. We find that interactions between residues in a C-terminally located transmembrane helix and in more N-terminally located helices can be detected already at the point when the C-terminal helix partitions from the translocon into the membrane. Our findings pinpoint the earliest

SUBMITTER: Cymer F 

PROVIDER: S-EPMC3767533 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature