The T/t-complex in the mouse: mutations that impair differentiation.

The T/t-complex in the mouse contains multiple genetic factors, capable of independent mutation and separable by recombination, that affect specific events of differentiation during embryonic development and spermatogenesis. Morphological and serological as well as biochemical studies have suggested that t-mutations are associated directly or indirectly with abnormalities of the cell surface. Recent efforts to identify the molecular nature of theses abnormalities gives evidence for at least two different types of molecules associated with complex lethal t-haplotypes. One molecule, a non-glycosylated protein of 63,000 daltons, is a direct gene product specified in apparently the same mutant form by each of over 30 independent t-haplotypes examined that contain the mutant gene responsible for tail interaction. On the other hand, the serologically defined antigenic determinants that define specific lethal t-haplotypes have been shown to reside on different oligosaccharides. The implication of these data with respect to the arrangement and function of mutant factors within the T/t-complex will be discussed.