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Structure of glutamate transporter homologue GltTk in unsaturated conditions - outward-outward-inward configurationStructure of glutamate transporter homologue GltTk in unsaturated conditions - outward-outward-inward configuration
Structural highlights
Publication Abstract from PubMedGlutamate transporters are cation-coupled secondary active membrane transporters that clear the neurotransmitter L-glutamate from the synaptic cleft. These transporters are homotrimers, with each protomer functioning independently by an elevator-type mechanism, in which a mobile transport domain alternates between inward- and outward-oriented states. Using single-particle cryo-EM we have determined five structures of the glutamate transporter homologue GltTk, a Na(+)- L-aspartate symporter, embedded in lipid nanodiscs. Dependent on the substrate concentrations used, the protomers of the trimer adopt a variety of asymmetrical conformations, consistent with the independent movement. Six of the 15 resolved protomers are in a hitherto elusive state of the transport cycle in which the inward-facing transporters are loaded with Na(+) ions. These structures explain how substrate-leakage is prevented - a strict requirement for coupled transport. The belt protein of the lipid nanodiscs bends around the inward oriented protomers, suggesting that membrane deformations occur during transport. Structural ensemble of a glutamate transporter homologue in lipid nanodisc environment.,Arkhipova V, Guskov A, Slotboom DJ Nat Commun. 2020 Feb 21;11(1):998. doi: 10.1038/s41467-020-14834-8. PMID:32081874[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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