3-(6-isobutyl-9-methoxy-1-4-dioxo-1-2-3-4-6-7-12-12a-octahydropyrazino(1--2--1-6)pyrido(3-4-b)indol-3-yl)propionic-acid-tert-butyl-ester and benzamil

ABCG1 is an ATP binding cassette (ABC) transporter that removes excess cholesterol from peripheral tissues. Despite its role in preventing lipid accumulation and the development of cardiovascular and metabolic disease, the mechanism underpinning ABCG1-mediated cholesterol transport is unknown. Here we report a cryo-EM structure of human ABCG1 at 4 Å resolution in an inward-open state, featuring sterol-like density in the binding cavity. Structural comparison with the multidrug transporter ABCG2 and the sterol transporter ABCG5/G8 reveals the basis of mechanistic differences and distinct substrate specificity. Benzamil and taurocholate inhibited the ATPase activity of liposome-reconstituted ABCG1, whereas the ABCG2 inhibitor Ko143 did not. Based on the structural insights into ABCG1, we propose a mechanism for ABCG1-mediated cholesterol transport.

Topics: Adenosine Triphosphate; Amiloride; Amino Acid Sequence; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP Binding Cassette Transporter, Subfamily G, Member 5; ATP Binding Cassette Transporter, Subfamily G, Member 8; Binding Sites; Biological Transport; Cholesterol; Cryoelectron Microscopy; Diketopiperazines; Gene Expression; HEK293 Cells; Heterocyclic Compounds, 4 or More Rings; Humans; Kinetics; Lipoproteins; Models, Molecular; Neoplasm Proteins; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Recombinant Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Substrate Specificity; Taurocholic Acid