A 37-KB RESTRICTION MAP OF THE HUMAN-IMMUNOGLOBULIN LAMBDA-VARIABLE LOCUS, VB CLUSTER, HARBORING 4 FUNCTIONAL GENES AND 2 NONCODING V-LAMBDA SEQUENCES

The human immunoglobulin lambda variable locus (IGLV) is mapped at chr omosome 22 band q11.1-q11.2. The 30 functional germline v-lambda genes sequenced untill now have been subgrouped into 10 families (V lambda 1 to V lambda 10). The number of V lambda genes has been estimated at approximately 70. This locus is formed by three gene clusters (VA, VB and VC) that encompass the variable coding genes (V) responsible for t he synthesis of lambda-type Ig light chains, and the J lambda-C lambda cluster with the joining segments and the constant genes. Recently th e entire variable lambda gene locus was mapped by contig methodology a nd its one-megabase DNA totally sequenced. All the known functional V- lambda genes and pseudogenes were located. We screened a human genomic DNA cosmid library and isolated a clone with an insert of 37 kb (cosm id 8.3) encompassing four functional genes (IGLV7S1, IGLV1S1, IGLV1S2 and IGLV5a), a pseudogene (V lambda A) and a vestigial sequence (vg1) to study in detail the positions of the restriction sites surrounding the V lambda genes. We genera ted a high resolution restriction map, l ocating 31 restriction sites in 37 kb of the VB cluster, a region rich in functional V lambda genes. This mapping information opens the pers pective for further RFLP studies and sequencing.