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Structure and evolutionary origin of the gene encoding a human serum mannose-binding protein.
M E Taylor1, P M Brickell, R K Craig
1Department of Medicine, St. Mary's Hospital Medical School, London, U.K.
The Biochemical Journal
|September 15, 1989
Summary
Researchers characterized the human mannose-binding protein (MBP) gene, revealing its exon-intron structure and promoter elements. This organization supports exon shuffling in evolution and suggests MBP is an acute-phase protein.
Area of Science:
- Molecular Biology
- Genetics
- Immunology
Background:
- The major human serum mannose-binding protein (MBP) plays a role in innate immunity.
- Understanding the genetic basis of MBP is crucial for elucidating its function and regulation.
Purpose of the Study:
- To determine the genomic structure of the human mannose-binding protein (MBP) gene.
- To investigate the evolutionary origins and regulatory mechanisms of human serum MBP.
Main Methods:
- cDNA sequencing and comparison with protein sequence.
- Oligonucleotide-directed cloning of the genomic DNA using cosmid libraries.
- Analysis of intron/exon structure and nucleotide sequences.
- Identification of consensus sequences in the promoter region.
Main Results:
- The N-terminal sequence of human MBP matched the predicted amino acid sequence from a cDNA clone.
- The human MBP gene's intron/exon structure closely resembles that of the rat MBP gene.
- Exon sequences showed variations compared to a previously published human cDNA clone.
- The MBP molecule's domains (signal peptide, cysteine-rich, collagen-like, neck, carbohydrate-binding) are each encoded by a separate exon.
- Consensus sequences in the promoter region suggest regulation as an acute-phase protein.
Conclusions:
- The exon-shuffling hypothesis for gene evolution is supported by the human MBP gene's structure.
- Human serum MBP is likely regulated as an acute-phase protein synthesized by the liver.