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In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes
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C-terminal phosphorylation of MRP2 modulates its interaction with PDZ proteins

Tamás Hegedüs1, Tamás Sessler, Robert Scott

  • 1Department of Molecular Cell Biology, Membrane Research Group of the Hungarian Academy of Sciences, National Medical Center, Diószegi u. 64, 1113 Budapest, Hungary.

Biochemical and Biophysical Research Communications
|March 5, 2003
PubMed

Insights

Phosphorylation of the multidrug resistance-associated protein 2 (MRP2) significantly alters its binding to PDZ proteins. This finding impacts understanding of MRP2 trafficking and function in epithelial cells.

Area of Science:

  • Molecular Cell Biology
  • Biochemistry
  • Membrane Transport Proteins

Background:

  • Multidrug resistance-associated protein 2 (MRP2) is an ATP-dependent export pump crucial for epithelial cell function.
  • Protein kinase C (PKC) is known to modulate MRP2 trafficking.
  • MRP2 possesses a C-terminal PDZ binding motif implicated in its cellular targeting.

Purpose of the Study:

  • To investigate the effect of MRP2 phosphorylation on its interaction with PDZ proteins.
  • To determine how phosphorylation at Ser(1542) influences MRP2 binding to specific PDZ domain-containing proteins.

Main Methods:

  • Examined the binding of wild-type MRP2 and its phosphorylation-mimicking mutants to various PDZ proteins (EBP50, E3KARP, PDZK1, IKEPP, beta2-syntrophin, SAP-97).
  • Studied the binding of PDZ proteins to other ABC proteins, CFTR and ABCA1.
  • Utilized a phosphorylated C-terminal MRP2 peptide to assess binding interactions.

Main Results:

  • Apically localized PDZ proteins showed strong binding to MRP2 and CFTR.
  • Beta2-syntrophin selectively bound to ABCA1.
  • Phosphorylation-mimicking MRP2 mutants and peptide exhibited significantly enhanced binding to IKEPP, EBP50, and EBP50's PDZ domains.

Conclusions:

  • Phosphorylation of the MRP2 PDZ binding motif profoundly affects its interaction with PDZ proteins.
  • This phosphorylation-dependent modulation likely plays a critical role in regulating MRP2 localization and function.

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