The mammalian and yeast translocon complexes comprise a characteristic Sec61 channel

Autor(en): Erdmann, Frank
Jung, Martin 
Maurer, Patrick
Harsman, Anke
Zimmermann, Richard
Wagner, Richard 
Stichwörter: ARCHITECTURE; Biochemistry & Molecular Biology; Biophysics; COMPONENTS; Endoplasmic reticulum; ENDOPLASMIC-RETICULUM; MEMBRANES; Protein translocation; PROTEIN-CONDUCTING CHANNEL; RECONSTITUTION; RIBOSOME; Sec61 complex
Erscheinungsdatum: 2010
Herausgeber: ACADEMIC PRESS INC ELSEVIER SCIENCE
Journal: BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Volumen: 396
Ausgabe: 3
Startseite: 714
Seitenende: 720
Zusammenfassung: 
In eukaryotes, protein translocation across and insertion into the membrane of the endoplasmic reticulum (ER) is facilitated by a protein-conducting channel, the Sec61 complex or translocon. In our previous electrophysiological studies, we characterized the mammalian Sec61 channel from Canis familiaris. Here we extended these initial results to the Sec61 channel from the yeast Saccharomyces cerevisiae and compared the basic electrophysiological properties of both channel preparations with respect to the gating behaviour, distribution of channel open states, ionic conductance, approximated pore dimensions, reversal potential and selectivity as well as voltage-dependent open probability. We found that the Sec61 complexes from both species displayed conformable characteristics of the highly dynamic channel in an intrinsically open state. In contrast, the bacterial Sec61-homologue, the SecYEG complex from Escherichia coli, displayed under the same experimental conditions significantly different properties residing in an intrinsically closed state. We therefore propose that considerable differences between the respective eukaryote and prokaryote protein-conducting channel units and their regulation exist. (C) 2010 Elsevier Inc. All rights reserved.
ISSN: 0006291X
DOI: 10.1016/j.bbrc.2010.04.168

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