Thy-1 variants of mouse lymphomas: biochemical characterization of the genetic defect.
The surface proteins of Thy-1 positive mouse lymphomas and Thy-1 negative variants were labeled by lactoperoxidase-catalyzed iodination and characterized by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulphate and by immunological studies. The loss of the serologically defined Thy-1 antigenic determinant correlated with the absence of a radioactive band corresponding to a T lymphocyte-specific surface glycoprotein, T25, on autoradiographs of the iodinated proteins of Thy-1 negative variants. Reexpression of Thy-1 on hybrid cells dervied from fusions of complementary Thy-1 negative variants correlated with the reappearance of T25. Quantitative absorption studies using an antiserum which specifically recognized T25 confirmed that the Thy-1 negative variants have no detectable T25 (less than 0.03 of that of the Thy-1 positive lines) on their surface. Biosynthetic labeling studies revealed that none of the Thy-1 negative variants synthesized T25. However, synthesis of an immunologically cross-reactive molecule could be detected in two variants. On the basis of these results, we propose a model which describes a possible structure of the Thy-1 antigenic determinant and explains the biochemical nature of the genetic lesions leading to the loss of Thy-1 in these variants.
D000818:Animals; D006023:Glycoproteins / Q000276:immunology; D006822:Hybrid Cells / Q000276:immunology; D007519:Isoantigens / Q000235:genetics; D008223:Lymphoma / Q000235:genetics* / Q000276:immunology; D051379:Mice; D009374:Neoplasms, Experimental / Q000235:genetics / Q000276:immunology
D006023:Glycoproteins; D007519:Isoantigens