title: Identification of residues in ABCG2 affecting protein trafficking and drug transport, using co-evolutionary analysis of ABCG sequences.
abstract: ABCG2 is an ABC (ATP-binding cassette) transporter with a physiological role in urate transport in the kidney and is also implicated in multi-drug efflux from a number of organs in the body. The trafficking of the protein and the mechanism by which it recognizes and transports diverse drugs are important areas of research. In the current study, we have made a series of single amino acid mutations in ABCG2 on the basis of sequence analysis. Mutant isoforms were characterized for cell surface expression and function. One mutant (I573A) showed disrupted glycosylation and reduced trafficking kinetics. In contrast with many ABC transporter folding mutations which appear to be 'rescued' by chemical chaperones or low temperature incubation, the I573A mutation was not enriched at the cell surface by either treatment, with the majority of the protein being retained in the endoplasmic reticulum (ER). Two other mutations (P485A and M549A) showed distinct effects on transport of ABCG2 substrates reinforcing the role of TM helix 3 in drug recognition and transport and indicating the presence of intracellular coupling regions in ABCG2.
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K.
authors: Ameena J
authors: AJ
authors: Haider
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K.
authors: Megan H
authors: MH
authors: Cox
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K.
authors: Natalie
authors: N
authors: Jones
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K.
authors: Alice J
authors: AJ
authors: Goode
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K.
authors: Katherine S
authors: KS
authors: Bridge
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K.
authors: Kelvin
authors: K
authors: Wong
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K.
authors: Deborah
authors: D
authors: Briggs
authors: School of Life Sciences, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, U.K. Ian.kerr@nottingham.ac.uk.
authors: Ian D
authors: ID
authors: Kerr
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D019943:Amino Acid Substitution; D019020:Directed Molecular Evolution; D057809:HEK293 Cells; D006801:Humans; D020125:Mutation, Missense; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D009363:Neoplasm Proteins
keywords: ATP-binding cassette (ABC) transporter; drug binding; glycosylation; trafficking; transmembrane helix