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Assignment of the complement serine protease genes C1r and C1s to chromosome 12 region 12p13
V C Nguyen1, M Tosi, M S Gross
1Clinique de Recherches de Génétique Médicale (INSERM U12), Hôpital des Enfants Malades, Paris, France.
Insights
The genes for C1r and C1s, crucial for complement system function, were mapped to chromosome 12. These homologous genes, likely arising from duplication, remain closely linked on the chromosome's short arm.
Area of Science:
- Immunology
- Genetics
- Molecular Biology
Background:
- C1r and C1s are serine protease zymogens integral to the first component of complement (C1).
- Structural and functional similarities suggest C1r and C1s may share a common ancestral gene through duplication.
- Gene-specific DNA probes confirm distinct genetic origins for C1r and C1s.
Purpose of the Study:
- To determine the chromosomal location of the human C1r and C1s genes.
- To investigate the linkage of these homologous genes.
- To identify potential polymorphic DNA markers for chromosome 12.
Main Methods:
- Human-rodent cell hybrid panel analysis for gene assignment.
- In situ hybridization for precise gene localization.
- DNA probe hybridization to confirm gene specificity.
Main Results:
- The C1r and C1s genes were independently assigned to human chromosome 12.
- In situ hybridization localized both genes to the p13 region on the short arm of chromosome 12.
- The C1r and C1s loci were identified as polymorphic DNA markers.
Conclusions:
- The homologous C1r and C1s genes are located in close proximity on chromosome 12p13, supporting their origin from a gene duplication event.
- These findings provide insights into the evolutionary relationship and chromosomal organization of complement genes.
- The identified C1r and C1s loci serve as valuable genetic markers for chromosome 12 studies.
Abstract:
C1r and C1s are distinct, but structurally and functionally similar, serine protease zymogens responsible for the enzymatic activity of the first component of complement (C1). Recent comparisons indicate a significant degree of sequence similarity between C1r and C1s and support the hypothesis that they are related by gene duplication. Complementary DNA probes for human C1r and C1s do not cross-hybridize even at mild stringency conditions and are therefore gene-specific. Using a panel of 25 human-rodent cell hybrids, we have independently assigned the C1r and the C1s genes to chromosome 12. In situ hybridization analyses were consistent with these assignments, showing in addition that both C1r and C1s are located on the short arm of the chromosome in the region p13. These data suggest that the homologous C1r and C1s genes have remained closely linked after duplication of a common ancestor. The C1r and C1s loci also provide useful polymorphic DNA markers for the short arm of chromosome 12.