C-terminal phosphorylation of MRP2 modulates its interaction with PDZ proteins

Biochem Biophys Res Commun. 2003 Mar 14;302(3):454-61. doi: 10.1016/s0006-291x(03)00196-7.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Blotting, Western
  • Dose-Response Relationship, Drug
  • Humans
  • Insecta
  • Mitochondrial Proteins*
  • Peptides / chemistry
  • Peptides / pharmacology
  • Phosphorylation*
  • Plasmids / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • Ribosomal Proteins / chemistry*
  • Ribosomal Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Serine / metabolism

Substances

  • MRP2 protein, S cerevisiae
  • Mitochondrial Proteins
  • Peptides
  • Ribosomal Proteins
  • Saccharomyces cerevisiae Proteins
  • Serine