The variable genes and gene families of the mouse immunoglobulin kappa locus

In this report 118 mouse V kappa genes are described which, together with t he 22 V kappa genes reported previously (T. Kirschbaum et al., Eur: J. Immu nol. 1998. 28: 1458-1466) amount to 140 genes that had been cloned and sequ enced in our laboratory. For 73 of them cDNAs are known, i.e. they have to be considered functional genes, although 10 genes of this group have 1-bp d eviations from the canonical promoter, splice site or heptanucleotide recom bination signal sequences. Twenty V kappa genes have been defined as only p otentially functional since they do not contain any defect, but no cDNAs ha ve been found (yet) for them. Of the 140 V kappa genes 47 are pseudogenes. There are indications that two to five V kappa genes or pseudogenes exist i n the kappa locus which we have not yet been able to clone. The 140 V kappa genes and pseudogenes were assigned to 18 gene families, 4 of them being o ne-member families. This differs from previous enumerations of the families only by the combination of the V kappa 9 and V kappa 10 families and by th e addition of the V kappa dv gene as a new separate family. Sequence identi ty usually was 80 % or above within the gene families and 55-80 % between g enes of different families. Many of the mouse V kappa gene families show si gnificant homologies to the human ones, indicating that in evolution V kapp a gene diversification predated the divergence of the primate and rodent cl ades.