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A physical map of the human regulator of complement activation gene cluster linking the complement genes CR1, CR2,
J Rey-Campos1, P Rubinstein, S Rodriguez de Cordoba
1Department of Immunogenetics, New York Blood Center 10021.
Insights
The human regulator of complement activation (RCA) gene cluster contains C4-binding protein (C4BP), C3b/C4b receptor (CR1), decay accelerating factor (DAF), and C3dg receptor (CR2) genes. These genes are tightly linked on an 800-kb DNA segment, suggesting mechanisms that limit recombination.
Area of Science:
- Human genetics
- Molecular biology
- Immunology
Background:
- The complement system is crucial for innate immunity.
- Regulators of complement activation (RCA) control complement system activity.
- Understanding the organization of RCA genes is important for studying complement-mediated diseases.
Purpose of the Study:
- To determine the physical organization and linkage of human RCA genes.
- To investigate the arrangement of C4-binding protein (C4BP), C3b/C4b receptor (CR1), decay accelerating factor (DAF), and C3dg receptor (CR2) genes.
Main Methods:
- Pulsed field gel electrophoresis (PFGE) was used for physical mapping.
- Analysis of DNA segments to determine gene linkage and order.
Main Results:
- The human RCA gene cluster spans an 800-kb DNA segment.
- Genes are physically linked and ordered as CR1-CR2-DAF-C4BP.
- Tight linkage observed between CR1 and C4BP loci, despite significant DNA distance.
Conclusions:
- The RCA gene cluster exhibits a specific gene order: CR1-CR2-DAF-C4BP.
- Mechanisms likely exist that interfere with recombination within this cluster.
- This organization may play a role in the coordinated regulation of complement activation.
Abstract:
We report the organization of the human genes encoding the complement components C4-binding protein (C4BP), C3b/C4b receptor (CR1), decay accelerating factor (DAF), and C3dg receptor (CR2) within the regulator of complement activation (RCA) gene cluster. Using pulsed field gel electrophoresis analysis these genes have been physically linked and aligned as CR1-CR2-DAF-C4BP in an 800-kb DNA segment. The very tight linkage between the CR1 and the C4BP loci, contrasted with the relative long DNA distance between these genes, suggests the existence of mechanisms interfering with recombination within the RCA gene cluster.