The Sec translocase.
The vast majority of proteins trafficking across or into the bacterial cytoplasmic membrane occur via the translocon. The translocon consists of the SecYEG complex that forms an evolutionarily conserved heterotrimeric protein-conducting membrane channel that functions in conjunction with a variety of ancillary proteins. For posttranslational protein translocation, the translocon interacts with the cytosolic motor protein SecA that drives the ATP-dependent stepwise translocation of unfolded polypeptides across the membrane. For the cotranslational integration of membrane proteins, the translocon interacts with ribosome-nascent chain complexes and membrane insertion is coupled to polypeptide chain elongation at the ribosome. These processes are assisted by the YidC and SecDF(yajC) complex that transiently interacts with the translocon. This review summarizes our current understanding of the structure-function relationship of the translocon and its interactions with ancillary components during protein translocation and membrane protein insertion. This article is part of a Special Issue entitled Protein translocation across or insertion into membranes.
du Plessis
David J F
DJ
Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen, 9751NN Haren, The Netherlands.
Nouwen
Nico
N
Driessen
Arnold J M
AJ
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D021381:Protein Transport; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins