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The gene encoding decay-accelerating factor (DAF) is located in the complement-regulatory locus on the long arm of
Insights
The delay-accelerating factor (DAF) gene, crucial for protecting cells from complement damage, is located on human chromosome 1. This finding links DAF to a family of related complement-regulatory genes.
Area of Science:
- Immunology
- Human Genetics
- Molecular Biology
Background:
- The delay-accelerating factor (DAF) is essential for protecting host cells from complement-mediated damage.
- DAF regulates the activation of C3 convertases on cell surfaces, a key step in complement cascade.
Purpose of the Study:
- To determine the chromosomal location of the human DAF gene.
- To investigate the linkage of the DAF gene with other complement-regulatory genes.
Main Methods:
- Somatic cell hybridization using hamster-human cell hybrids to map the DAF gene.
- In situ hybridization on human metaphase chromosomes to refine gene localization.
Main Results:
- The DAF gene was mapped to human chromosome 1, specifically to bands 1q31-41.
- Gene localization was further refined to band 1q32, showing close linkage to complement receptor genes.
Conclusions:
- The DAF gene is located on the long arm of human chromosome 1.
- DAF is part of a gene family involved in complement regulation, sharing homologous repeats and functional activities.
Abstract:
Delay-accelerating factor (DAF) protects host cells from complement-mediated damage by regulating the activation of C3 convertases on host cell surfaces. Using a panel of hamster-human somatic cell hybrids, the DAF gene was mapped to human chromosome 1. In situ hybridization studies using human metaphase cells further localized the gene to bands 1q31-41, with the largest cluster of grains at 1q32. This establishes the close linkage of the DAF gene to genes for four other proteins (C3b/C4b receptor or complement receptor 1, C3d receptor or complement receptor 2, factor H, and C4-binding protein) that share 60-amino-acid homologous repeats as well as complement-regulatory or -receptor activity, thereby enlarging the complement-regulatory gene family on the long arm of human chromosome 1.