Delta is the Cx-gene product in the gamma/delta antigen receptor of dendritic epidermal cells

Abstract

Most T cells bear an antigen receptor that is a protein of a disulphide-linked heterodimer composed of an alpha chain and a beta chain associated with the non-polymorphic CD3 (T3) complex. A small subpopulation of thymic and peripheral T cells, as well as Thy-1+dendritic epidermal cells (dEC), express an alternative CD3-associated dimeric receptor composed of the product of the T-cell antigen receptor (TCR) gamma gene and a fourth chain, designated delta. Recently a new murine TCR constant-region gene, designated Cx, has been cloned and proposed as a candidate for the C delta gene. We have previously demonstrated that murine Thy-1+ dEC cell lines express a CD3-associated disulphide-linked heterodimer composed of a relative molecular mass Mr 41,000 (41K) gamma chain and a 50K delta chain. We have further analysed the receptor of one of these cloned dEC lines, 7-17.1, by endoglycosidase treatment of the isolated gamma and delta chains. The gamma chain was found to contain two N-linked oligosaccharide residues, consistent with the expression of a chain encoded by the V gamma 3 and C gamma 1 gene segments. The delta chain contains at least three N-linked oligosaccharides and has a core size of 38K. Northern blot analysis indicated the presence of abundant Cx messenger RNA in 7-17.1 cells. Immunoprecipitation with two antisera to peptides comprising distinct regions of the Cx sequence indicates that the delta chain is encoded by the Cx gene.