Junctional diversity in Xenopus immunoglobulin light chains

Xenopus cDNA sequences encoding the homolog of mammalian kappa (kappa) ligh t (L) chains were isolated from isogenic tadpole and adult individuals to i nvestigate whether there existed stage-specific immunoglobulin L chain expr ession and somatic diversification. In the course of these studies rearrang ements to a sixth J(L) gene segment and a pseudogene (J(L)psi) were found, and it is suggested that the order of these gene segments with respect to t he L chain constant (C) region exon is: J(L)6-J(L)1-J(L)2-J(L)3-J(L)4-J(L)5 -J(L)psi-C-L. The cDNA junctional diversity was analyzed; few N and P regio ns were found and almost all the CDR3 were 9 codons in length. There were r estricted patterns of recombination site resolution, and this is attributed to some constraint in J(L) coding end processing. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.