title: Inhibition of protein translocation across the endoplasmic reticulum membrane by sterols.
abstract: Cholesterol and related sterols are known to modulate the physical properties of biological membranes and can affect the activities of membrane-bound protein complexes. Here, we report that an early step in protein translocation across the endoplasmic reticulum (ER) membrane is reversibly inhibited by cholesterol levels significantly lower than those found in the plasma membrane. By UV-induced chemical cross-linking we further show that high cholesterol levels prevent cross-linking between ribosome-nascent chain complexes and components of the Sec61 translocon, but have no effect on cross-linking to the signal recognition particle. The inhibiting effect on translocation is different between different sterols. Our data suggest that the protein translocation machinery may be sensitive to changes in cholesterol levels in the ER membrane.
authors.affiliation: Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: I
authors.initials: I
authors.lastname: Nilsson
authors.forename: H
authors.initials: H
authors.lastname: Ohvo-Rekilä
authors.forename: J P
authors.initials: JP
authors.lastname: Slotte
authors.forename: A E
authors.initials: AE
authors.lastname: Johnson
authors.forename: G
authors.initials: G
authors.lastname: von Heijne
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D011506:Proteins; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle; D002784:Cholesterol