The Murine Thy-1 Gene

Abstract

The Thy-1 antigen is a small glycoprotein found in large amounts at the cell surface of brain cells and rodent thymocytes, and in lesser quantities on a number of other tissues (Campbell et al. 1981). In many of these tissues, the level of expression of Thy-1 has been shown to vary during differentiation in the mouse, Thy-1 occurs in two allotypic forms referred to as Thy-1.1 (AKR) and Thy-1.2 (Balb/c and others) (Reif and Allen 1964) coded for by a gene that maps on chromosome 9 (Blankenhorn and Douglas 1972). In contrast, in humans only one allotypic form is known coded for by a gene that maps on chromosome 11 (van Rijs et al. 1985). Structural and sequence homologies between the Thy-1 glycoprotein and immunoglobulin (Ig) domains and other members of the Ig superfamily have led to the suggestion that Thy-1 may represent the primordial Ig domain (Williams and Gagnon 1982) lending support to the argument that the immune system may have evolved from the nervous system. Thus, the study of the Thy-1 gene is interesting, both from the point of view of its structure and the mechanisms which control its tissue-specific expression.