Abstract
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.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Adenosine Triphosphatases / metabolism
-
Carrier Proteins / metabolism*
-
Cell Membrane / metabolism
-
Endoplasmic Reticulum / metabolism
-
Guanine Nucleotide Exchange Factors / metabolism
-
Membrane Proteins / genetics
-
Membrane Proteins / isolation & purification
-
Membrane Proteins / metabolism*
-
Mutation
-
Peptide Chain Termination, Translational
-
Protein Binding
-
Protein Multimerization
-
Recombinant Proteins / genetics
-
Recombinant Proteins / isolation & purification
-
Recombinant Proteins / metabolism
-
Ribosomal Proteins / metabolism
-
Ribosomes / metabolism*
-
Saccharomyces cerevisiae / genetics
-
Saccharomyces cerevisiae / metabolism
-
Saccharomyces cerevisiae Proteins / genetics
-
Saccharomyces cerevisiae Proteins / isolation & purification
-
Saccharomyces cerevisiae Proteins / metabolism*
-
Signal Recognition Particle / metabolism
-
Ubiquitin / genetics
-
Ubiquitin / isolation & purification
-
Ubiquitin / metabolism*
Substances
-
Carrier Proteins
-
GET4 protein, S cerevisiae
-
Guanine Nucleotide Exchange Factors
-
Mdy2 protein, S cerevisiae
-
Membrane Proteins
-
Recombinant Proteins
-
Ribosomal Proteins
-
Saccharomyces cerevisiae Proteins
-
Sgt2 protein, S cerevisiae
-
Signal Recognition Particle
-
Ubiquitin
-
Adenosine Triphosphatases
-
Get3 protein, S cerevisiae