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
✍ Scribed by Shunyou Wang; Deborah L. Diamond; G. Michael Hass; Roger Sokoloff; Robert L. Vessella
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- French
- Weight
- 117 KB
- Volume
- 92
- Category
- Article
- ISSN
- 0020-7136
- DOI
- 10.1002/ijc.1272
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✦ Synopsis
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.