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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.

Pubmed ID: 12615054

Authors

  • Hegedüs T
  • Sessler T
  • Scott R
  • Thelin W
  • Bakos E
  • Váradi A
  • Szabó K
  • Homolya L
  • Milgram SL
  • Sarkadi B

Journal

Biochemical and biophysical research communications

Publication Data

March 14, 2003

Associated Grants

None

Mesh Terms

  • Amino Acid Motifs
  • Animals
  • Blotting, Western
  • Dose-Response Relationship, Drug
  • Humans
  • Insects
  • Mitochondrial Proteins
  • Peptides
  • Phosphorylation
  • Plasmids
  • Protein Binding
  • Protein Structure, Tertiary
  • Ribosomal Proteins
  • Saccharomyces cerevisiae Proteins
  • Serine