IDENTIFICATION AND PURIFICATION OF A M-R-75,0000 CELL-SURFACE HUMAN MELANOMA-ASSOCIATED ANTIGEN

  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (6) , 2310-2316
Abstract
Surface macromolecules on cultured human melanoma cells were radioiodinated by a lactoperoxidase method. Macromolecules shed into culture medium were collected, concentrated and fractionated on Sepharose 6B and lentil lectin-Sepharose. Radioactivity associated with macromolecules was assayed by precipitation with trichloroacetic acid, and that associated with melanoma-associated antigens (MAA) was assayed by specific immunoprecipitation with xenogeneic anti-melanoma serum. Following the last step in purification, .apprx. 2/3 of the acid-insoluble radioactivity in the most MAA-active fraction was associated with this antigen. MAA concentration in this fraction .apprx. 200-fold greater than that in cells, and it contained a single labeled protein band by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The MAA was a glycoprotein consisting of a single polypeptide chain with a MW of .apprx. 75,000. This antigen was common to several but not to all melanomas. It was not detected, or was present in much decreased concentration, in 16 other unreleated allogeneic or xenogeneic normal and malignant cells. It was immunologically unrelated to serum albumin or fibronectin. A highly purified MW of 75,000 cell surface component of human melanoma cells which appears to be a MAA, was produced.