Accurate 5′ Splice-Site Selection in Mouse κ Immunoglobulin Light Chain Premessenger RNAs is not Cell-Type-Specific

• Published in: Proceedings of the National Academy of Sciences - PNAS 1987-11, Vol.84 (22), p.7928-7932
• Main Authors: Kedes, Dean H., Steitz, Joan A.
• Format: Article
• Language: English
• Subjects: Animals; B-Lymphocytes - metabolism; Biological and medical sciences; Cell Line; Cell lines; DNA, Recombinant; Exons; Fundamental and applied biological sciences. Psychology; Gene expression; Genes; Genes, Immunoglobulin; HeLa cells; HeLa Cells - metabolism; Humans; Immunoglobulin kappa-Chains - genetics; Immunoglobulin Switch Region; Introns; Lymphocytes; Mice; Molecular and cellular biology; Molecular genetics; Organ Specificity; RNA; RNA Precursors - genetics; RNA Splicing; Splicing; Transfection; Untranslated regions
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.84.22.7928

In mature mouse B lymphocytes, immunoglobulin κ light chain transcripts contain an intervening sequence separating the recombined variable (V) plus joining (J) exon from the distant constant (C) exon. After V--J recombination, this intervening sequence can include as many as three unused but very similar J-region 5′ splice sites. Each of these sites is potentially functional if the gene is appropriately recombined. It is unclear how the splicing machinery distinguishes among these 5′ splice sites, always choosing the most upstream site. We used synthetic transcripts of κ gene sequences containing J3 and J4 in both the germ-line and the recombined configurations to study the pattern of 5′ splice-site selection in vitro. We find that both HeLa cell and lymphocyte nuclear extracts fail to discriminate between the J3- and J4-region 5′ splice sites. In contrast, after transfection into HeLa cells, similar κ light chain transcripts are spliced correctly at the most upstream 5′ splice site--that which is used in κ -producing cells. We conclude that accurate 5′ splice-site selection in the mouse κ light chain is neither cell-type- nor species-specific. Potential mechanisms for this controlling step in gene expression are discussed.