The human immunoglobulin kappa locus consists of two copies that are organized in opposite polarity

Abstract

The kappa locus is a largely duplicated structure from which a 600-kb C kappa proximal (p) and a 440-kb distal (d) contig have been cloned. In parallel with the cloning and sequencing work, the kappa locus and its surroundings were mapped by pulsed-field gel electrophoresis (PFGE) with the help of 13 rare-cutter restriction nucleases and 15 unique hybridization probes. The distance between the two contigs was determined to be about 800 kb and the size of the entire locus about 2.0 Mb. The map extends 1.5 Mb toward the centromere and 3.5 Mb toward the telomere (including the CD8 alpha locus; see accompanying paper by Weichhold et al. (1993b) Genomics 16:512-514), yielding a continuously mapped region of 7 Mb. The detailed map of the kappa locus and its close vicinity allows a number of conclusions to be drawn: (1) The kappa locus comprises two copies that include the above contigs. It constitutes a structure that, starting from a center in the still uncloned region, is largely symmetrical for about 850 kb to each side. The two contigs are therefore arranged in opposite 5'-3' polarity; this explains the structures of the products of V kappa-J kappa rearrangements found in lymphoid cells arising by deletions or inversions, respectively. (2) The organization of the kappa locus and its surroundings is very similar, although of course not identical, in three cell lines and 12 individuals.(ABSTRACT TRUNCATED AT 250 WORDS)