A potentially functional V kappa gene at a distance of 1.5 Mb from the immunoglobulin kappa locus.

An amplicon that is highly homologous to a part of the human kappa locus was found at the 3' or telomeric side of C kappa at a distance of about 1.5 Mb. From analysis of sequence divergence, it is concluded that the amplicon was formed after the duplication of the kappa locus, which may have taken place about 1 million years ago. A V kappa gene of subgroup III within the amplicon turned out to have no defects in its sequence and to have a 5'-3' orientation opposite to the one of J kappa C kappa. Theoretically, a functional V kappa-J kappa-C kappa gene could be formed by an inversion mechanism, but no rearrangement products were observed so far.