6s7p

Nucleotide bound ABCB4

Loading... Status: waiting for Mol* initialization Structural highlights 6s7p is a 1 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.2Å Ligands: ATP, CLR, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Disease MDR3_HUMAN Low phospholipid-associated cholelithiasis;Progressive familial intrahepatic cholestasis type 3;Intrahepatic cholestasis of pregnancy. The disease is caused by mutations affecting the gene represented in this entry. The disease is caused by mutations affecting the gene represented in this entry. The disease is caused by mutations affecting the gene represented in this entry. Function MDR3_HUMAN Energy-dependent phospholipid efflux translocator that acts as a positive regulator of biliary lipid secretion. Functions as a floppase that translocates specifically phosphatidylcholine (PC) from the inner to the outer leaflet of the canalicular membrane bilayer into the canaliculi of hepatocytes. Translocation of PC makes the biliary phospholipids available for extraction into the canaliculi lumen by bile salt mixed micelles and therefore protects the biliary tree from the detergent activity of bile salts (PubMed:7957936, PubMed:8898203, PubMed:9366571, PubMed:17523162, PubMed:23468132, PubMed:24806754, PubMed:24723470, PubMed:24594635, PubMed:21820390). Plays a role in the recruitment of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM) molecules to nonraft membranes and to further enrichment of SM and cholesterol in raft membranes in hepatocytes (PubMed:23468132). Required for proper phospholipid bile formation (By similarity). Indirectly involved in cholesterol efflux activity from hepatocytes into the canalicular lumen in the presence of bile salts in an ATP-dependent manner (PubMed:24045840). Promotes biliary phospholipid secretion as canaliculi-containing vesicles from the canalicular plasma membrane (PubMed:9366571, PubMed:28012258). In cooperation with ATP8B1, functions to protect hepatocytes from the deleterious detergent activity of bile salts (PubMed:21820390). Does not confer multidrug resistance (By similarity).[UniProtKB:P21440] Publication Abstract from PubMed ABCB4 is an ATP-binding cassette transporter that extrudes phosphatidylcholine into the bile canaliculi of the liver. Its dysfunction or inhibition by drugs can cause severe, chronic liver disease or drug-induced liver injury. We determined the cryo-EM structure of nanodisc-reconstituted human ABCB4 trapped in an ATP-bound state at a resolution of 3.2 A. The nucleotide binding domains form a closed conformation containing two bound ATP molecules, but only one of the ATPase sites contains bound Mg(2+). The transmembrane domains adopt a collapsed conformation at the level of the lipid bilayer, but we observed a large, hydrophilic and fully occluded cavity at the level of the cytoplasmic membrane boundary, with no ligand bound. This indicates a state following substrate release but prior to ATP hydrolysis. Our results rationalize disease-causing mutations in human ABCB4 and suggest an 'alternating access' mechanism of lipid extrusion, distinct from the 'credit card swipe' model of other lipid transporters. Structure of the human lipid exporter ABCB4 in a lipid environment.,Olsen JA, Alam A, Kowal J, Stieger B, Locher KP Nat Struct Mol Biol. 2019 Dec 23. pii: 10.1038/s41594-019-0354-3. doi:, 10.1038/s41594-019-0354-3. PMID:31873305 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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