Phosphorylation of PDZ1 domain attenuates NHERF-1 binding to cellular targets.

Published

Journal Article

NHERF-1 (Na(+)-H(+) exchanger regulatory factor 1, also known as EBP50 ezrin-binding protein of 50 kDa) is a phosphoprotein that assembles multiprotein complexes via two PDZ domains and a C-terminal ezrin-binding domain. Current work utilized metabolic labeling in cultured cells expressing wild type GFP-NHERF-1 to define the physiological importance of NHERF-1 phosphorylation. Treatment of cells with phosphatase inhibitors calyculin A and okadaic acid enhanced NHERF-1 phosphorylation and inhibited its dimerization. Eliminating C-terminal serines abolished the modulation of NHERF-1 dimerization by phosphatase inhibitors and identified the phosphorylation of the PDZ1 domain that attenuated its binding to physiological targets, including beta(2)-adrenergic receptor, platelet-derived growth factor receptor, cystic fibrosis transmembrane conductance regulator, and sodium-phosphate cotransporter type IIa. The major covalent modification of PDZ1 was mapped to serine 77. Confocal microscopy of cultured cells suggested key roles for PDZ1 and ERM-binding domain in localizing NHERF-1 at the cell surface. The substitution S77A eliminated PDZ1 phosphorylation and increased NHERF-1 localization at the cell periphery. In contrast, S77D reduced NHERF-1 colocalization with cortical actin cytoskeleton. These data suggested that serine 77 phosphorylation played key role in modulating NHERF-1 association with plasma membrane targets and identified a novel mechanism by which PDZ1 phosphorylation may transduce hormonal signals to regulate the function of membrane proteins in epithelial tissues.

Full Text

Duke Authors

Cited Authors

  • Voltz, JW; Brush, M; Sikes, S; Steplock, D; Weinman, EJ; Shenolikar, S

Published Date

  • November 16, 2007

Published In

Volume / Issue

  • 282 / 46

Start / End Page

  • 33879 - 33887

PubMed ID

  • 17895247

Pubmed Central ID

  • 17895247

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M703481200

Language

  • eng

Conference Location

  • United States