| Autor: |
Zhang Y; Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.; BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany., De Laurentiis E; Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.; Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), Göttingen, Germany., Bohnsack KE; Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany., Wahlig M; Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.; BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany., Ranjan N; Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany., Gruseck S; Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.; BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany., Hackert P; Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany., Wölfle T; Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.; BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany., Rodnina MV; Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), Göttingen, Germany.; Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany., Schwappach B; Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany. blanche.schwappach@med.uni-goettingen.de.; Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), Göttingen, Germany. blanche.schwappach@med.uni-goettingen.de., Rospert S; Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany. sabine.rospert@biochemie.uni-freiburg.de.; BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany. sabine.rospert@biochemie.uni-freiburg.de. |
| Abstrakt: |
The guided entry of tail-anchored proteins (GET) pathway assists in the posttranslational delivery of tail-anchored proteins, containing a single C-terminal transmembrane domain, to the ER. Here we uncover how the yeast GET pathway component Get4/5 facilitates capture of tail-anchored proteins by Sgt2, which interacts with tail-anchors and hands them over to the targeting component Get3. Get4/5 binds directly and with high affinity to ribosomes, positions Sgt2 close to the ribosomal tunnel exit, and facilitates the capture of tail-anchored proteins by Sgt2. The contact sites of Get4/5 on the ribosome overlap with those of SRP, the factor mediating cotranslational ER-targeting. Exposure of internal transmembrane domains at the tunnel exit induces high-affinity ribosome binding of SRP, which in turn prevents ribosome binding of Get4/5. In this way, the position of a transmembrane domain within nascent ER-targeted proteins mediates partitioning into either the GET or SRP pathway directly at the ribosomal tunnel exit. |
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