title: C-terminal phosphorylation of MRP2 modulates its interaction with PDZ proteins.
abstract: MRP2, a member of the ABC protein superfamily, functions as an ATP-dependent export pump for anionic conjugates in the apical membranes of epithelial cells. It has been reported that the trafficking of MRP2 is modulated by PKC. Adjacent to the C-terminal PDZ binding motif, which may be involved in the targeting of MRP2, we found a potential PKC phosphorylation site (Ser(1542)). Therefore, we examined the interaction of MRP2 and its phosphorylation-mimicking mutants with different PDZ proteins (EBP50, E3KARP, PDZK1, IKEPP, beta2-syntrophin, and SAP-97). The binding of these PDZ proteins to CFTR and ABCA1, other ABC proteins, possessing PDZ binding motif, was also studied. We observed a strong binding of apically localized PDZ proteins to both MRP2 and CFTR, whereas beta2-syntrophin exhibited binding only to ABCA1. The phosphorylation-mimicking MRP2 mutant and a phosphorylated C-terminal MRP2 peptide showed significantly increased binding to IKEPP, EBP50, and both individual PDZ domains of EBP50. Our results suggest that phosphorylation of the MRP2 PDZ binding motif has a profound effect on the PDZ binding of MRP2.
authors.affiliation: Department of Molecular Cell Biology, Membrane Research Group of the Hungarian Academy of Sciences, National Medical Center, Diószegi u. 64, 1113 Budapest, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Hegedüs
authors.forename: Tamás
authors.initials: T
authors.lastname: Sessler
authors.forename: Robert
authors.initials: R
authors.lastname: Scott
authors.forename: William
authors.initials: W
authors.lastname: Thelin
authors.forename: Eva
authors.initials: E
authors.lastname: Bakos
authors.forename: András
authors.initials: A
authors.lastname: Váradi
authors.forename: Katalin
authors.initials: K
authors.lastname: Szabó
authors.forename: László
authors.initials: L
authors.lastname: Homolya
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Milgram
authors.forename: Balázs
authors.initials: B
authors.lastname: Sarkadi
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D015153:Blotting, Western; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007313:Insecta; D024101:Mitochondrial Proteins; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine / Q000378:metabolism
chemical_list: C093947:MRP2 protein, S cerevisiae; D024101:Mitochondrial Proteins; D010455:Peptides; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine