The J κ proximal region of the human K locus contains three uncommon V κ genes which are arranged in opposite transcriptional polarities

Abstract

The structure of one of the V κ gene-containing regions of the locus coding for the human immunoglobulin light chains of the K type is described. This so-called B region contains three genes: B1, B2 and B3. According to its sequence B1 is a pseudogene which does not fit well into the present subgroup classification. In lymphoid cell lines the B1 gene region is frequently deleted. B2 and B3 are the previously reported EV15 and V κIV genes. The transcriptional polarity of the B1 gene is found to be opposite to one of the B2 and B3 genes. This observation together with the fact that the B region is proximal to the J κC κ gene segment leads to the conclusions to the mechanism of the V κ−J κ recombination and allows us to explain the formation of the recombination products in a particular cell line by two consecutive inversions.