title: Role of the N-terminal transmembrane region of the multidrug resistance protein MRP2 in routing to the apical membrane in MDCKII cells.
abstract: In polarized cells, the multidrug resistance protein MRP2 is localized in the apical plasma membrane, whereas MRP1, another multidrug resistance protein (MRP) family member, is localized in the basolateral membrane. MRP1 and MRP2 are thought to contain an N-terminal region of five transmembrane segments (TMD(0)) coupled to 2 times six transmembrane segments via an intracellular loop (L(0)). We previously demonstrated for MRP1 that a mutant lacking TMD(0) but still containing L(0), called L(0)DeltaMRP1, was functional and routed to the lateral plasma membrane. To investigate the role of the TMD(0)L(0) region of MRP2 in routing to the apical membrane, we generated mutants similar to those made for MRP1. In contrast to L(0)DeltaMRP1, L(0)DeltaMRP2 was associated with an intracellular compartment, most likely endosomes. Co-expression with TMD(0), however, resulted in apical localization of L(0)DeltaMRP2 and transport activity. Uptake experiments with vesicles containing L(0)DeltaMRP2 demonstrated that the molecule is able to transport LTC(4). An MRP2 mutant without TMD(0)L(0), DeltaMRP2, was only core-glycosylated and localized intracellularly. Co-expression of DeltaMRP2 with TMD(0)L(0) resulted in an increased protein level of DeltaMRP2, full glycosylation of the protein, routing to the apical membrane, and transport activity. Our results suggest that the TMD(0) region is required for routing to or stable association with the apical membrane.
authors.affiliation: Georg-Speyer-Haus, Paul Ehrlich Strasse 42-44, 60596 Frankfurt am Main, Germany.
authors.forename: Sara B Mateus
authors.initials: SB
authors.lastname: Fernández
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Holló
authors.forename: Andras
authors.initials: A
authors.lastname: Kern
authors.forename: Eva
authors.initials: E
authors.lastname: Bakos
authors.forename: Paul A
authors.initials: PA
authors.lastname: Fischer
authors.forename: Piet
authors.initials: P
authors.lastname: Borst
authors.forename: Raymond
authors.initials: R
authors.lastname: Evers
mesh_terms: D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000502:physiology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry; D004285:Dogs; D006031:Glycosylation; D017997:Leukotriene C4 / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry* / Q000502:physiology; D009097:Multienzyme Complexes / Q000502:physiology; D046988:Proteasome Endopeptidase Complex; D013329:Structure-Activity Relationship; D014747:Vinblastine / Q000378:metabolism
chemical_list: D003546:Cysteine Endopeptidases; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D017997:Leukotriene C4; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009097:Multienzyme Complexes; D046988:Proteasome Endopeptidase Complex; D014747:Vinblastine; C421109:multidrug resistance-associated protein 1