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8QRQ

ASCT2 protomer in lipid nanodiscs with bound glutamine and Na+ ions in the outward-facing state (OFS.2)

Summary for 8QRQ
Entry DOI10.2210/pdb8qrq/pdb
Related8QRO 8QRP 8QRQ 8QRR 8QRS 8QRU 8QRV 8QRW
EMDB information18621 18622 18623 18624 18625 18626 18627 18628
DescriptorNeutral amino acid transporter B(0), SODIUM ION, GLUTAMINE (3 entities in total)
Functional Keywordsneutral amino acid exchanger amino acid transport system elevator transporter glutamine transport, transport protein
Biological sourceHomo sapiens (human)
Total number of polymer chains1
Total formula weight57682.91
Authors
Borowska, A.,Rheinberger, J.,Paulino, C.,Slotboom, D.J. (deposition date: 2023-10-09, release date: 2024-08-14)
Primary citationBorowska, A.M.,Chiariello, M.G.,Garaeva, A.A.,Rheinberger, J.,Marrink, S.J.,Paulino, C.,Slotboom, D.J.
Structural basis of the obligatory exchange mode of human neutral amino acid transporter ASCT2.
Nat Commun, 15:6570-6570, 2024
Cited by
PubMed Abstract: ASCT2 is an obligate exchanger of neutral amino acids, contributing to cellular amino acid homeostasis. ASCT2 belongs to the same family (SLC1) as Excitatory Amino Acid Transporters (EAATs) that concentrate glutamate in the cytosol. The mechanism that makes ASCT2 an exchanger rather than a concentrator remains enigmatic. Here, we employ cryo-electron microscopy and molecular dynamics simulations to elucidate the structural basis of the exchange mechanism of ASCT2. We establish that ASCT2 binds three Na ions per transported substrate and visits a state that likely acts as checkpoint in preventing Na ion leakage, both features shared with EAATs. However, in contrast to EAATs, ASCT2 retains one Na ion even under Na-depleted conditions. We demonstrate that ASCT2 cannot undergo the structural transition in TM7 that is essential for the concentrative transport cycle of EAATs. This structural rigidity and the high-affinity Na binding site effectively confine ASCT2 to an exchange mode.
PubMed: 39095408
DOI: 10.1038/s41467-024-50888-8
PDB entries with the same primary citation
Experimental method
ELECTRON MICROSCOPY (2.74 Å)
Structure validation

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