The human lambda L chain Ig locus. Recharacterization of JC lambda 6 and identification of a functional JC lambda 7.
The human lambda L chain Ig gene complex consists of multiple JC gene segments. A seventh human lambda C region gene segment, C lambda 7, was found 2.7 kb downstream 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 lamba 7 as compared to that of JC lambda 2 and JC lambda 3.
Bauer
T R
TR
Department of Microbiology and Immunology (R138), University of Miami School of Medicine, FL 33101.
Blomberg
B
B
D000595:Amino Acid Sequence; D001483:Base Sequence; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007128:Immunoglobulin Fragments / Q000235:genetics*; D007133:Immunoglobulin Joining Region / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007146:Immunoglobulin lambda-Chains / Q000235:genetics; D008214:Lymphocytes / Q000276:immunology; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D007127:Immunoglobulin Constant Regions; D007128:Immunoglobulin Fragments; D007133:Immunoglobulin Joining Region; D007147:Immunoglobulin Light Chains; D007146:Immunoglobulin lambda-Chains