8wjh
From Proteopedia
Cryo-EM structure of human protein B
Structural highlights
FunctionS22AB_HUMAN Antiporter that mediates the transport of conjugated steroids and other specific organic anions at the basal membrane of syncytiotrophoblast and at the apical membrane of proximal tubule epithelial cells, in exchange for anionic compounds (PubMed:10660625, PubMed:11907186, PubMed:15037815, PubMed:15102942, PubMed:15291761, PubMed:15576633, PubMed:17229912, PubMed:18501590, PubMed:26277985, PubMed:28027879). May be responsible for placental absorption of fetal-derived steroid sulfates such as estrone sulfate (E1S) and the steroid hormone precursor dehydroepiandrosterone sulfate (DHEA-S), as well as clearing waste products and xenobiotics from the fetus (PubMed:12409283). Maybe also be involved in placental urate homeostasis (PubMed:17229912). Facilitates the renal reabsorption of organic anions such as urate and derived steroid sulfates (PubMed:15037815, PubMed:17229912). Organic anion glutarate acts as conteranion for E1S renal uptake (PubMed:15037815, PubMed:17229912). Possible transport mode may also include DHEA-S/E1S exchange (PubMed:28027879). Also interacts with inorganic anions such as chloride and hydroxyl ions, therefore possible transport modes may include E1S/Cl(-), E1S/OH(-), urate/Cl(-) and urate/OH(-) (PubMed:17229912). Also mediates the transport of prostaglandin E2 (PGE2) and prostaglandin F2-alpha (PGF2-alpha) and may be involved in their renal excretion (PubMed:11907186). Also able to uptake anionic drugs, diuretics, bile salts and ochratoxin A (PubMed:10660625, PubMed:26277985). Mediates the unidirectional efflux of glutamate and aspartate (PubMed:28027879). Glutamate efflux down its transmembrane gradient may drive SLC22A11/OAT4-mediated placental uptake of E1S (PubMed:26277985).[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] Publication Abstract from PubMedHigh serum urate levels are the major risk factor for gout. URAT1, the primary transporter for urate absorption in the kidneys, is well known as an anti-hyperuricemia drug target. However, the clinical application of URAT1-targeted drugs is limited because of their low specificity and severe side effects. The lack of structural information impedes elucidation of the transport mechanism and the development of new drugs. Here, we present the cryoelectron microscopy (cryo-EM) structures of human URAT1(R477S), its complex with urate, and its closely related homolog OAT4. URAT1(R477S) and OAT4 exhibit major facilitator superfamily (MFS) folds with outward- and inward-open conformations, respectively. Structural comparison reveals a 30 degrees rotation between the N-terminal and C-terminal domains, supporting an alternating access mechanism. A conserved arginine (OAT4-Arg473/URAT1-Arg477) is found to be essential for chloride-mediated inhibition. The URAT1(R477S)-urate complex reveals the specificity of urate recognition. Taken together, our study promotes our understanding of the transport mechanism and substrate selection of URAT1. Structural basis for the transport and substrate selection of human urate transporter 1.,He J, Liu G, Kong F, Tan Q, Wang Z, Yang M, He Y, Jia X, Yan C, Wang C, Qian H Cell Rep. 2024 Aug 14;43(8):114628. doi: 10.1016/j.celrep.2024.114628. PMID:39146184[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found References
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