Yeast artificial chromosome contigs reveal that distal variable-region genes reside at least 3 megabases from the joining regions in the murine immunoglobulin kappa locus

The immunoglobulin kappa gene locus encodes 95% of the light chains of murine antibody molecules and is thought to contain up to 300 variable (V-kappa)-region genes generally considered to comprise 20 families. To delineate the locus we have isolated 29 yeast artificial chromosome genomic clones that form two contigs, span >3.5 megabases, and contain two known non-imnunoglobulin kappa markers. Using PCR primers specific for 19 V-kappa gene families and Southern analysis, we have refined the genetically defined order of these V-kappa gene families. Of these, V(kappa)2 maps at least 3.0 Mb from the joining (J(kappa)) region and appears to be the most distal V-kappa gene segment.