Related Experiment Videos
Identification of the second heparin-binding domain in human complement factor H
T K Blackmore1, J Hellwage, T A Sadlon
1Department of Microbiology and Infectious Diseases, Flinders Medical Centre, Bedford Park, South Australia. tim.blackmore@flinders.edu.au
Journal of Immunology (Baltimore, Md. : 1950)
|April 8, 1998
Summary
Complement factor H has two heparin binding sites. These sites are located in SCR 7 and SCR 20, which are crucial for regulating complement activation on sialic acid-rich surfaces.
Area of Science:
- Immunology
- Biochemistry
Background:
- Complement factor H (fH) regulates the alternative complement pathway.
- fH prevents complement activation on sialic acid-rich surfaces.
- Heparin binding serves as a model for fH's sialic acid-binding properties.
Purpose of the Study:
- To identify all heparin-binding sites within complement factor H.
- To investigate the role of specific Short Consensus Repeat (SCR) modules in heparin binding.
Main Methods:
- Preparation of recombinant truncated and SCR deletion mutants of fH.
- Heparin-agarose affinity chromatography to test heparin binding.
- Analysis of fH-related proteins (FHR-3 and FHR-4) for heparin binding.
Main Results:
- SCR 7 was previously identified as a heparin-binding site.
- SCRs 16-20, specifically SCR 20, were found to contain another heparin binding site.
- Deletion of both SCR 7 and SCR 20 abolished heparin binding.
- FHR-3, containing an SCR homologous to fH's SCR 7, bound heparin, while FHR-4 did not.
Conclusions:
- Complement factor H possesses two distinct heparin binding sites.
- These sites are located in SCR 7 and SCR 20.
- SCR 20 requires adjacent SCRs (18-19) for effective heparin binding.