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Structure of the human homo-hexameric LRRC8A channel at 4.25 Angstroms
Structural highlights
Disease[LRC8A_HUMAN] Autosomal agammaglobulinemia. The disease is caused by mutations affecting the gene represented in this entry. A chromosomal aberration involving LRRC8 has been found in a patient with congenital agammaglobulinemia. Translocation t(9;20)(q33.2;q12). The translocation truncates the LRRC8 gene, resulting in deletion of the eighth, ninth, and half of the seventh LRR domains. Function[LRC8A_HUMAN] Essential component of the volume-regulated anion channel (VRAC, also named VSOAC channel), an anion channel required to maintain a constant cell volume in response to extracellular or intracellular osmotic changes (PubMed:24725410, PubMed:24790029, PubMed:26530471, PubMed:26824658, PubMed:28193731, PubMed:29769723). The VRAC channel conducts iodide better than chloride and can also conduct organic osmolytes like taurine (PubMed:24725410, PubMed:24790029, PubMed:26530471, PubMed:26824658, PubMed:28193731). Mediates efflux of amino acids, such as aspartate and glutamate, in response to osmotic stress (PubMed:28193731). LRRC8A and LRRC8D are required for the uptake of the drug cisplatin (PubMed:26530471). Required for in vivo channel activity, together with at least one other family member (LRRC8B, LRRC8C, LRRC8D or LRRC8E); channel characteristics depend on the precise subunit composition (PubMed:24790029, PubMed:26824658, PubMed:28193731). Can form functional channels by itself (in vitro) (PubMed:26824658). Involved in B-cell development: required for the pro-B cell to pre-B cell transition (PubMed:14660746). Also required for T-cell development (By similarity).[UniProtKB:Q80WG5][1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedMaintenance of cell volume against osmotic change is crucial for proper cell functions. Leucine-rich repeat-containing 8 proteins are anion-selective channels that extrude anions to decrease the cell volume on cellular swelling. Here, we present the structure of human leucine-rich repeat-containing 8A, determined by single-particle cryo-electron microscopy. The structure shows a hexameric assembly, and the transmembrane region features a topology similar to gap junction channels. The LRR region, with 15 leucine-rich repeats, forms a long, twisted arc. The channel pore is located along the central axis and constricted on the extracellular side, where highly conserved polar and charged residues at the tip of the extracellular helix contribute to permeability to anions and other osmolytes. Two structural populations were identified, corresponding to compact and relaxed conformations. Comparing the two conformations suggests that the LRR region is flexible and mobile, with rigid-body motions, which might be implicated in structural transitions on pore opening. Cryo-EM structures of the human volume-regulated anion channel LRRC8.,Kasuya G, Nakane T, Yokoyama T, Jia Y, Inoue M, Watanabe K, Nakamura R, Nishizawa T, Kusakizako T, Tsutsumi A, Yanagisawa H, Dohmae N, Hattori M, Ichijo H, Yan Z, Kikkawa M, Shirouzu M, Ishitani R, Nureki O Nat Struct Mol Biol. 2018 Aug 20. pii: 10.1038/s41594-018-0109-6. doi:, 10.1038/s41594-018-0109-6. PMID:30127360[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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