The human lambda L chain Ig locus. Recharacterization of JC lambda 6 and identification of a functional JC lambda 7
Bauer, T.R.; Blomberg, B.
Journal of Immunology 146(8): 2813-2820
1991
ISSN/ISBN: 0022-1767 PMID: 1901886 Document Number: 377977
The human .lambda. L chain Ig gene complex consists of multiple JC gene segments. A seventh haman .lambda. C region gene segment, C.lambda.7, was found 2.7 kb down-stream of C.lambda.6 in this gene complex. A J .lambda. gene segment, J.lambda.7, was found 1.2 kb upstream of C.lambda.7 and contains potentially functional nonamer and heptamer recombination sites, an RNA splice site and J coding region. C.lambda.7 maintains an open reading frame and encodes a new .lambda. isotype. C.lambda.7 encodes Kern+ and Oz- determinants, but does not encode any of the Kern+Oz- myeloma proteins published to date. Nevertheless, we present evidence that JC.lambda.7 is transcribed in normal lymphocytes and is functional. In contrast, we present new data that the C.lambda.6 gene segment, reported by others to encode the Kern+Oz- protein, is non-functional due to a 4-bp insertion in our cosmid clone. The 4-bp insertion was characterized further in 32 genomic DNA samples by producing a distinctive restriction fragment length and verified by the DNA sequences of the polymerase chain reaction products of two different cell lines. We discuss the possibility that the Kern+Oz- myeloma proteins do not define an isotype and are not encoded by JC.lambda.7 nor other non-allelic genes, and we discuss the level of expression of JC.lambda.7 as compared to that of JC.lambda.2 and JC.lambda.3.