Identification of major binding proteins and substrates for the SH2-containing protein tyrosine phosphatase SHP-1 in macrophages

Mol Cell Biol. 1998 Jul;18(7):3838-50. doi: 10.1128/mcb.18.7.3838.

Abstract

The protein tyrosine phosphatase SHP-1 is a critical regulator of macrophage biology, but its detailed mechanism of action remains largely undefined. SHP-1 associates with a 130-kDa tyrosyl-phosphorylated species (P130) in macrophages, suggesting that P130 might be an SHP-1 regulator and/or substrate. Here we show that P130 consists of two transmembrane glycoproteins, which we identify as PIR-B/p91A and the signal-regulatory protein (SIRP) family member BIT. These proteins also form separate complexes with SHP-2. BIT, but not PIR-B, is in a complex with the colony-stimulating factor 1 receptor (CSF-1R), suggesting that BIT may direct SHP-1 to the CSF-1R. BIT and PIR-B bind preferentially to substrate-trapping mutants of SHP-1 and are hyperphosphorylated in macrophages from motheaten viable mice, which express catalytically impaired forms of SHP-1, indicating that these proteins are SHP-1 substrates. However, BIT and PIR-B are hypophosphorylated in motheaten macrophages, which completely lack SHP-1 expression. These data suggest a model in which SHP-1 dephosphorylates specific sites on BIT and PIR-B while protecting other sites from dephosphorylation via its SH2 domains. Finally, BIT and PIR-B associate with two tyrosyl phosphoproteins and a tyrosine kinase activity. Tyrosyl phosphorylation of these proteins and the level of the associated kinase activity are increased in the absence of SHP-1. Our data suggest that BIT and PIR-B recruit multiple signaling molecules to receptor complexes, where they are regulated by SHP-1 and/or SHP-2.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Differentiation*
  • Histocompatibility Antigens / metabolism*
  • Intracellular Signaling Peptides and Proteins
  • Macrophages / metabolism*
  • Membrane Glycoproteins / metabolism*
  • Mice
  • Mice, Inbred C3H
  • Mice, Inbred C57BL
  • Nerve Tissue Proteins
  • Neural Cell Adhesion Molecule L1*
  • Neural Cell Adhesion Molecules / metabolism*
  • Phosphorylation
  • Phosphotyrosine
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases / genetics
  • Protein Tyrosine Phosphatases / metabolism*
  • Receptor, Macrophage Colony-Stimulating Factor / metabolism
  • Receptors, Immunologic*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • SH2 Domain-Containing Protein Tyrosine Phosphatases
  • Substrate Specificity
  • src Homology Domains*

Substances

  • Antigens, Differentiation
  • Histocompatibility Antigens
  • Intracellular Signaling Peptides and Proteins
  • Membrane Glycoproteins
  • Nerve Tissue Proteins
  • Neural Cell Adhesion Molecule L1
  • Neural Cell Adhesion Molecules
  • Receptors, Immunologic
  • Recombinant Fusion Proteins
  • transplantation antigen P91A, mouse
  • Phosphotyrosine
  • Receptor, Macrophage Colony-Stimulating Factor
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases
  • Ptpn11 protein, mouse
  • Ptpn6 protein, mouse
  • SH2 Domain-Containing Protein Tyrosine Phosphatases