Binding of phosphatidic acid to the protein-tyrosine phosphatase SHP-1 as a basis for activity modulation

Biochemistry. 1999 Sep 14;38(37):11993-2002. doi: 10.1021/bi982586w.

Abstract

Activation of the SH2 domain-possessing protein-tyrosine phosphatase SHP-1 by acidic phospholipids as phosphatidic acid (PA) has been described earlier and suggested to participate in regulation of SHP-1 activity toward cellular substrates. The mechanism of this activation is poorly understood. Direct binding of phosphatidic acid to recombinant SHP-1 could be demonstrated by measuring the extent of [(14)C]PA binding in a chromatographic assay, by measuring the extent of binding of SHP-1 to PA-coated ELISA plates or silica beads (TRANSIL), and by spectroscopic assays employing fluorescently labeled PA liposomes. In addition to PA, phosphatidylinositol 3,4, 5-trisphosphate (PIP3), dipalmitoylphosphatidylglycerol, phosphatidylinositol 4,5-bisphosphate, and phosphatidylserine (PS) were found to bind to SHP-1, albeit to a lesser extent. A high-affinity binding site for PA and PIP3 was mapped to the 41 C-terminal amino acids of SHP-1. This site was absent from the related protein-tyrosine phosphatase SHP-2 and conferred activation of SHP-1 by PA toward two different substrates at low lipid concentrations. A SHP-1 mutant missing this binding site could, however, still be activated toward phosphorylated myelin basic protein as a substrate at high PA concentrations. This activation is likely to be mediated by a second, low-affinity binding site for PA in the N-terminal part of SHP-1 within the SH2 domains. High-affinity phospholipid binding to the C-terminus of SHP-1 may present a specific mechanism of regulating activity and/or cellular localization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Enzyme Activation
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Lipid Metabolism
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Phosphatidic Acids / chemistry
  • Phosphatidic Acids / metabolism*
  • Phosphopeptides / chemistry
  • Phosphopeptides / metabolism
  • Protein Binding
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases / chemistry
  • Protein Tyrosine Phosphatases / genetics
  • Protein Tyrosine Phosphatases / metabolism*
  • SH2 Domain-Containing Protein Tyrosine Phosphatases
  • Substrate Specificity
  • src Homology Domains*

Substances

  • Intracellular Signaling Peptides and Proteins
  • Peptide Fragments
  • Phosphatidic Acids
  • Phosphopeptides
  • PTPN11 protein, human
  • PTPN6 protein, human
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases
  • SH2 Domain-Containing Protein Tyrosine Phosphatases