Identification of Three New Ig Lambda-Like Genes in Man

摘要

An antibody molecule is constructed from four polypeptides, two identical L chains,(k or lambda), and two identical H chains. In its germline state, Ig k L chain DNA exists in three discrete groups of noncontiguous segments: V, J, and C. H chain -related DNA is slightly more complex, and includes a fourth group of discrete D segments. To form a functioal L chain gene, one V region undergoes a site-specific recombination event and becomes contiguous with one J segment. H chain gene formation is a slightly more complicated variation on this theme, which includes the rearrangement of a D segment to a J segment before V-D recombination. Antibody diversity can be accounted for by combinations obtained from this V-J(or V-D-J) joining and the association within a cell of such recombined L ad H chain genes. Three new human lambda L lchain-like Ig genes are identified by restriction enzyme and nucleotide sequence analysis. Two genes, 14.1 and 16.1, have intact J and C regions, and are potentially functional, with open reading frames. A third gene, 18.1, is a pseudogene. The evolutionary lineage of these genes compared to the known functional locus lambda c sub 1- lambda c sub 6 can be surmised from Southern blot and nucleotide homologies. This study demonstrates that the human lambda gene family is more complex than previously recognized. Keywords: Immunoglobulins; Recombinant DNA; Gene sequencing; Gene evolution; Immune system.