Yeast Artificial Chromosome Contigs Reveal that Distal Variable-Region Genes Reside at Least 3 Megabases from the Joining Regions in the Murine Immunoglobulin κ Locus

The immunoglobulin κ gene locus encodes 95% of the light chains of murine antibody molecules and is thought to contain up to 300 variable (Vκ)-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-immunoglobulin κ markers. Using PCR primers specific for 19 Vκgene families and Southern analysis, we have refined the genetically defined order of these Vκgene families. Of these, Vκ2 maps at least 3.0 Mb from the joining (Jκ) region and appears to be the most distal Vκgene segment.