Mapping of Igk-V genes using backcrossed laboratory and wild mice.

In the mouse, the genes coding for the Ly-2 antigen, the beta chain of the T-cell receptor, and the immunoglobulin kappa light chain have been located on chromosome 6. Although a tentative order has been proposed for these genes, very few data have been reported concerning their genetic distance. To address this question, we have produced backcross mice between SJL and MAI (a wild-derived strain belonging to the Mus musculus), since these mice segregate for the Ly-2 and Igk-C proteins and for the Igk-V24, Igk-V21, Igk-V10, Igk-V8, and Igk-V4 genes. Twelve recombinants were obtained from 163 backcross mice studied. Two mice showed a recombination between the (Igk-V24, Igk-V10, Igk-V8, Igk-V4) and the (Ly-2, Igk-C, Igk-V21) groups, and ten mice displayed a recombination between the (Igk-V24, Igk-V10, Igk-V8, Igk-V4) group and the Tcrb-C loci. These data imply the following gene order: Tcrb-C .... (Igk-V24, Igk-V10, Igk-V8, Igk-V4) .... (Igk-V21, Igk-C, Ly-2). They indicate a distance of 6.1 cM between Tcrb-C and (Igk-V24, Igk-V10, Igk-V8, Igk-V4) and 1.2 cM between Igk-V24, Igk-V10, Igk-V8, Igk-V4 and the (Igk-V21, Igk-C, Ly-2) groups.