Abstract
Targeting of newly synthesized membrane proteins to the endoplasmic reticulum is an essential cellular process. Most membrane proteins are recognized and targeted co-translationally by the signal recognition particle. However, nearly 5% of membrane proteins are 'tail-anchored' by a single carboxy-terminal transmembrane domain that cannot access the co-translational pathway. Instead, tail-anchored proteins are targeted post-translationally by a conserved ATPase termed Get3. The mechanistic basis for tail-anchored protein recognition or targeting by Get3 is not known. Here we present crystal structures of yeast Get3 in 'open' (nucleotide-free) and 'closed' (ADP.AlF(4)(-)-bound) dimer states. In the closed state, the dimer interface of Get3 contains an enormous hydrophobic groove implicated by mutational analyses in tail-anchored protein binding. In the open state, Get3 undergoes a striking rearrangement that disrupts the groove and shields its hydrophobic surfaces. These data provide a molecular mechanism for nucleotide-regulated binding and release of tail-anchored proteins during their membrane targeting by Get3.
Publication types
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Research Support, N.I.H., Intramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Adenosine Diphosphate / metabolism
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Adenosine Triphosphatases / chemistry*
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Adenosine Triphosphatases / metabolism*
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Adenosine Triphosphate / metabolism
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Aluminum Compounds / chemistry
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Aluminum Compounds / metabolism
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Crystallography, X-Ray
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Fluorides / chemistry
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Fluorides / metabolism
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Guanine Nucleotide Exchange Factors / chemistry*
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Guanine Nucleotide Exchange Factors / metabolism*
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Hydrophobic and Hydrophilic Interactions
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Membrane Proteins / chemistry
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Membrane Proteins / metabolism*
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Methanococcus
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Models, Molecular
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Protein Binding
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Protein Conformation
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Protein Multimerization
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SEC Translocation Channels
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Saccharomyces cerevisiae / chemistry*
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / metabolism*
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Structure-Activity Relationship
Substances
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Aluminum Compounds
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Guanine Nucleotide Exchange Factors
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Membrane Proteins
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SEC Translocation Channels
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Saccharomyces cerevisiae Proteins
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tetrafluoroaluminate
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Adenosine Diphosphate
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Adenosine Triphosphate
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Adenosine Triphosphatases
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Get3 protein, S cerevisiae
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Fluorides