C-terminal phosphorylation of MRP2 modulates its interaction with PDZ proteins.
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.
Hegedüs
Tamás
T
Department of Molecular Cell Biology, Membrane Research Group of the Hungarian Academy of Sciences, National Medical Center, Diószegi u. 64, 1113 Budapest, Hungary.
Sessler
Tamás
T
Scott
Robert
R
Thelin
William
W
Bakos
Eva
E
Váradi
András
A
Szabó
Katalin
K
Homolya
László
L
Milgram
Sharon L
SL
Sarkadi
Balázs
B
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
C093947:MRP2 protein, S cerevisiae; D024101:Mitochondrial Proteins; D010455:Peptides; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine