The human λ L chain Ig gene complex consists of multiple JC gene segments. A seventh human λ C region gene segment, Cλ7, was found 2.7 kb downstream of Cλ6 in this gene complex. A J λ gene segment, Jλ7, was found 1.2 kb upstream of Cλ7 and contains potentially functional nonamer and heptamer recombination sites, an RNA splice site and J coding region. Cλ7 maintains an open reading frame and encodes a new λ isotype. Cλ7 encodes Kern+ and Oz- determinants, but does not encode any of the Kern+Oz- myeloma proteins published to date. Nevertheless, we present evidence that JCλ7 is transcribed in normal lymphocytes and is functional. In contrast, we present new data that the Cλ6 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 JCλ7 nor other non-allelic genes, and we discuss the level of expression of JCλ7 as compared to that of JCλ2 and JCλ3.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Immunology|
|State||Published - 1991|
ASJC Scopus subject areas
- Immunology and Allergy