title: The amino terminus of the human multidrug resistance transporter ABCC1 has a U-shaped folding with a gating function.
abstract: Multidrug resistance is a serious problem in successful cancer chemotherapy. Studies using model cell lines have demonstrated that overexpression of some members of the ATP-binding cassette (ABC) transporter superfamily, such as ABCC1, causes enhanced efflux and, thus, decreased accumulation of multiple anticancer drugs, which leads to increased cell survival. Unlike most other ABC transporters, ABCC1 has an additional membrane-spanning domain (MSD0) with a putative extracellular amino terminus of 32 amino acids. However, the function of MSD0 and the role of the extracellular amino terminus are largely unknown. In this study, we examined the structural folding and the function of the amino terminus. We found that it has a U-shaped folding with the bottom of the U-structure facing cytoplasm and both ends in extracellular space. We also found that this U-shaped amino terminus probably functions as a gate to regulate the drug transport activity of human ABCC1.
authors.affiliation: Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
authors.forename: Qun
authors.initials: Q
authors.lastname: Chen
authors.forename: Youyun
authors.initials: Y
authors.lastname: Yang
authors.forename: Lang
authors.initials: L
authors.lastname: Li
authors.forename: Jian-Ting
authors.initials: JT
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D002469:Cell Separation; D002470:Cell Survival; D004351:Drug Resistance; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry; D017353:Gene Deletion; D006801:Humans; D008969:Molecular Sequence Data; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D000939:Epitopes; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C421109:multidrug resistance-associated protein 1