Genomic structure of the human Ig lambda 1 gene suggests that it may be expressed as an Ig lambda 14.1-like protein or as a canonical B cell Ig lambda light chain: implications for Ig lambda gene evolution.
In pre-B cells, immunoglobulin mu (Ig mu) is associated with pre-B cell-specific proteins to form a multimeric complex that is found on the cell surface. One of these proteins is encoded by the three exon Ig lambda-like gene 14.1, whose expression is restricted to pre-B cells and occurs from an unrearranged gene. A comparison of the 14.1 gene structure to the seven-gene human Ig lambda locus revealed that the most 5' gene, Ig lambda 1, is organized in a three-exon structure very similar to the 14.1 gene. Transcription and splicing of these three-exon sequences would lead to an mRNA with an open reading frame which could encode a light (L) chain-like protein with a molecular weight of 23,045. Our analysis suggests that two transcripts may be produced from the Ig lambda 1 gene that share the same Ig lambda 1 constant region-containing third exon. One transcript would include all three 14.1-related exons and be expressed from the germline gene, and the second transcript would be produced after variable-joining (V-J) recombination has occurred to Ig lambda J1 and would encode a classic Ig lambda L chain protein. The conservation of the genomic organization of the human 14.1 and Ig lambda 1 genes and the mouse homolog, lambda 5, relative to the classic Ig lambda L chain genes provides insight into the evolution of Ig genes.
Department of Biological Sciences, Monsanto Company, Saint Louis, Missouri 63198.
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Evans
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Hollis
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D005075:Biological Evolution; D015152:Blotting, Northern; D005091:Exons / Q000235:genetics; D015870:Gene Expression; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D005803:Genes, Immunoglobulin / Q000235:genetics*; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000235:genetics*; D007146:Immunoglobulin lambda-Chains / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics
D007147:Immunoglobulin Light Chains; D007146:Immunoglobulin lambda-Chains; D015345:Oligonucleotide Probes; D012313:RNA