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Nucleotide-free form of S. pombe Get3
Structural highlights
FunctionGET3_SCHPO ATPase required for the post-translational delivery of tail-anchored (TA) proteins to the endoplasmic reticulum. Recognizes and selectively binds the transmembrane domain of TA proteins in the cytosol. This complex then targets to the endoplasmic reticulum by membrane-bound receptors, where the tail-anchored protein is released for insertion. This process is regulated by ATP binding and hydrolysis. ATP binding drives the homodimer towards the closed dimer state, facilitating recognition of newly synthesized TA membrane proteins. ATP hydrolysis is required for insertion. Subsequently, the homodimer reverts towards the open dimer state, lowering its affinity for the membrane-bound receptor, and returning it to the cytosol to initiate a new round of targeting (By similarity).[HAMAP-Rule:MF_03112] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTargeting 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. The structural basis of tail-anchored membrane protein recognition by Get3.,Mateja A, Szlachcic A, Downing ME, Dobosz M, Mariappan M, Hegde RS, Keenan RJ Nature. 2009 Sep 17;461(7262):361-6. Epub 2009 Aug 12. PMID:19675567[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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