Gene transfer of the ly‐3 chain gene of the mouse cd8 molecular complex: co‐transfer with the ly‐2 polypeptide gene results in detectable cell surface expression of the ly‐3 antigenic determinants

摘要

AbstractThe CD8 molecule is a glycoprotein expressed on a subset of mature T lymphocytes. It has been postulated to be a receptor for class I major histocompatibility complex molecules. In the mouse, CD8 is a heterodimer composed of Ly‐2 and Ly‐3 chains. We have isolated and analyzed cDNA and cosmid clones corresponding to the Ly‐3 subunit. One of the isolated, cosmid clones was subsequently transfected, alone or in combination with the Ly‐2 gene, into mouse Ltk−cells. Analysis of the Ly‐2,3 molecules expressed at the surface of the double transfectants indicated that they are serologically and biochemically indistinguishable from their normal counterparts expressed on lymphoid cells. Ltk−cells transfected with the Ly‐2 gene alone were shown to react with a subset of antLCD8 monoclonal antibodies whereas Ly‐3 transfectants did not stain with any of the anti‐Ly‐3 antibodies employed in this study. Since at least one of these antibodies (53‐5.8) has been previously shown to recognize an epitope which is retained on the Ly‐3 subunit after dissociation of the heterodimeric Ly‐2,3 complex, these observations suggest that the expression of the Ly‐2 polypeptide is required to permit the detectable cell surface expression of the antigenic determinant