title: N-linked glycans do not affect plasma membrane localization of multidrug resistance protein 4 (MRP4) but selectively alter its prostaglandin E2 transport activity.
abstract: Multidrug resistance protein 4 (MRP4) is a member of subfamily C of the ATP-binding cassette superfamily of membrane transport proteins. MRP4 mediates the ATP-dependent efflux of many endogenous and exogenous solutes across the plasma membrane, and in polarized cells, it localizes to the apical or basolateral plasma membrane depending on the tissue type. MRP4 is a 170 kDa glycoprotein and here we show that MRP4 is simultaneously N-glycosylated at Asn746 and Asn754. Furthermore, confocal immunofluorescence studies showed that N-glycans do not affect MRP4's apical membrane localization in polarized LLC-PK1 cells or basolateral membrane localization in polarized MDCKI cells. However, vesicular transport assays showed that N-glycans differentially affect MRP4's ability to transport prostaglandin E2, but not estradiol glucuronide. Together these data indicate that N-glycosylation at Asn746 and Asn754 is not essential for plasma membrane localization of MRP4 but cause substrate-selective effects on its transport activity.
authors.affiliation: Department of Pathology & Molecular Medicine, Cancer Research Institute, Queen's University, 10 Stuart Street, Kingston, K7L 3N6, Ontario, Canada; Division of Cancer Biology & Genetics, Cancer Research Institute, Queen's University, 10 Stuart Street, Kingston, K7L 3N6, Ontario, Canada.
authors.forename: M Fahad
authors.initials: MF
authors.lastname: Miah
authors.affiliation: Division of Cancer Biology & Genetics, Cancer Research Institute, Queen's University, 10 Stuart Street, Kingston, K7L 3N6, Ontario, Canada.
authors.forename: Gwenaëlle
authors.initials: G
authors.lastname: Conseil
authors.affiliation: Department of Pathology & Molecular Medicine, Cancer Research Institute, Queen's University, 10 Stuart Street, Kingston, K7L 3N6, Ontario, Canada; Division of Cancer Biology & Genetics, Cancer Research Institute, Queen's University, 10 Stuart Street, Kingston, K7L 3N6, Ontario, Canada. Electronic address: spc.cole@queensu.ca.
authors.forename: Susan P C
authors.initials: SP
authors.lastname: Cole
mesh_terms: D000818:Animals; D002462:Cell Membrane; D015232:Dinoprostone / Q000378:metabolism*; D004285:Dogs; D006031:Glycosylation; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D018374:LLC-PK1 Cells; D061985:Madin Darby Canine Kidney Cells; D026901:Membrane Transport Proteins / Q000378:metabolism*; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D013552:Swine; D014018:Tissue Distribution
chemical_list: D015232:Dinoprostone; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011134:Polysaccharides; C073492:ABCC4 protein, human
keywords: ABC transporter; MRP4; Membrane localization; N-glycosylation; Polarized kidney cells; Prostaglandin E(2) transport