Identification of prostate specific membrane antigen (PSMA) as the target of monoclonal antibody 107-1A4 by proteinchip; array, surface-enhanced laser desorption/ionization (SELDI) technology

Int J Cancer. 2001 Jun 15;92(6):871-6. doi: 10.1002/ijc.1272.


Recently we described the generation of the prostate tissue-specific monoclonal antibody (MAb) 107-1A4, its expression pattern and preliminary targeting of human prostate cancer xenografts. In this report we demonstrate that the target antigen for MAb 107-1A4 is prostate-specific membrane antigen (PSMA) using immunoaffinity absorption followed by SDS-PAGE and mass spectrometric analysis of peptides produced by in-gel tryptic digestion. The identity of the antigen has been confirmed by Western blots using MAbs of known specificity. MAb 107-1A4 is not reactive on Western blots. The conformational epitope for 107-1A4 is on the extracellular domain of PSMA. In competition studies, the binding of MAb 107-1A4 to LNCaP cells is inhibited by itself but not by any other of several other anti-PSMA MAbs, suggesting that the epitope may be unique. These results suggest that 107-1A4 is reactive to a conformational epitope in the external domain of PSMA that is unique among the panel of anti-PSMA MAbs in this study. Furthermore this work demonstrates the ability of mass spectroscopy to elucidate antibody-ligand interaction.

MeSH terms

  • Antibodies, Monoclonal / analysis
  • Antibodies, Monoclonal / chemistry*
  • Antigens, Surface*
  • Binding, Competitive
  • Blotting, Western
  • Carboxypeptidases / chemistry*
  • Electrophoresis, Agar Gel
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes
  • Glutamate Carboxypeptidase II
  • Humans
  • Ligands
  • Mass Spectrometry / methods*
  • Oligonucleotide Array Sequence Analysis*
  • Precipitin Tests
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • Trypsin / metabolism
  • Tumor Cells, Cultured


  • 107-1A4 monoclonal antibody
  • Antibodies, Monoclonal
  • Antigens, Surface
  • Epitopes
  • Ligands
  • Carboxypeptidases
  • FOLH1 protein, human
  • Glutamate Carboxypeptidase II
  • Trypsin