Ribosome-bound Get4/5 facilitates the capture of tail-anchored proteins by Sgt2 in yeast.

Autor: Zhang, Ying, De Laurentiis, Evelina, Bohnsack, Katherine E., Wahlig, Mascha, Ranjan, Namit, Gruseck, Simon, Hackert, Philipp, Wölfle, Tina, Rodnina, Marina V., Schwappach, Blanche, Rospert, Sabine
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Zdroj: Nature Communications; 2/4/2021, Vol. 12 Issue 1, p1-17, 17p
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. The guided entry of tail-anchored proteins (GET) pathway assists in the delivery of such proteins to the ER. Here, the authors reveal that the pathway components Get4/5 probe a region near the ribosomal exit tunnel. Upon emergence of a client protein, Get4/5 recruits Sgt2 and initiates the targeting phase of the pathway. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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