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Recent duplication of the two human CD8 beta-chain genes
K Nakayama1, Y Kawachi, S Tokito
1Laboratory of Molecular Regulation of Aging, Frontier Research Program, Tsukuba-City, Japan.
Journal of Immunology (Baltimore, Md. : 1950)
|March 15, 1992
Summary
Researchers identified two CD8 beta genes (CD8 beta 1 and beta 2) with high similarity. Despite both appearing functional, all observed CD8 beta forms originate from the CD8 beta 1 gene via alternative splicing.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- The T cell surface glycoprotein CD8 plays a crucial role in immune responses.
- Alternative splicing of CD8 beta-chain transcripts generates diverse functional forms.
Purpose of the Study:
- To investigate the gene organization and duplication of the human CD8 beta-chain.
- To determine the origin of the different CD8 beta cDNA forms.
Main Methods:
- Isolation and analysis of cDNA clones encoding the CD8 beta-chain.
- Gene organization analysis, including exon-intron structure and nucleotide sequencing.
- Pulse field gel electrophoresis to determine gene location.
Main Results:
- Discovery of two recently duplicated CD8 beta genes: CD8 beta 1 (9 exons) and CD8 beta 2 (7 exons).
- High sequence similarity between CD8 beta 1 and CD8 beta 2 genes, including introns.
- CD8 beta 1 and CD8 beta 2 genes are located over 1.5 Mb apart on chromosome 2, with CD8 beta 1 upstream of the CD8 alpha gene.
- All five distinct CD8 beta cDNA forms found in thymus, PBL, and HPB-ALL cells are derived from the CD8 beta 1 gene through alternative splicing.
Conclusions:
- The human genome contains two highly similar, recently duplicated CD8 beta genes.
- Despite the apparent functionality of both CD8 beta 1 and CD8 beta 2 genes, only CD8 beta 1 serves as the source for the diverse CD8 beta transcripts observed in T cells.