The human complement factor H protein family consists of the complement and immune regulators factor H, the factor H-like protein 1(FHL-1) and five factor H-related proteins (FHR-1 to -5) (2). Members of this family are exclusively composed of individually folded protein domains, termed short consensus repeats (SCRs) or complement control modules. The genes of this family have been located in human chromosome 1q32, which is known as the regulators of complement activation (RCA) gene clusters (3). FHR-5 has been identified initially as a universal component of complement deposits (1), and detected in glomerular immune deposits (4). The pattern of deposits is similar to other complement components, suggesting that FHR-5 may play a role in complement activation and regulation. It is synthesized in the liver and consists of 9 SCRs. Its biological function is not understood fully. FHR-5 exhibits similar characteristics as those of factor H in heparin binding, CRP binding, and lipoprotein association (5). Weak factor I-dependent cofactor activity for C3b cleavage has also been observed (5).
Source:A DNA sequence encoding human complement factor H related 5 by the CFHR5 gene (human CFHR5, amino acid residues 1 to 569, NP_110414) (1) was expressed with a C-terminal 10 His tag in a murine myeloma cell line, NS0.
Molecular Mass:The purified, secreted rhCFHR5 has a major N-terminal sequence of E19GTLCDFPKI. The 561 amino acid residue rhCFHR5 predicts a molecular mass of 64 kD and migrates with an apparent molecular mass of approximately 73kD in SDS-PAGE under reducing conditions.
Endotoxin Level:< 1.0 EU per 1 μg of the protein as determined by the LAL method.
Activity:Measured by its ability to inhibit the binding of biotinylated rhCFHR5 to immobilized rhCRP (McRae, JL., et al., 2005, J. Immunol. 174:6250).
Reconstitution:It is recommended that sterile PBS be added to the vial to prepare a working stock solution of no less than 100ug/ml. The carrier-free protein should be used immediately upon reconstitution to avoid losses in activity due to non-specific binding to the inside surface of the vial. For long term storage as a dilute solution, a carrier protein (e.g. 0.1% HSA or BSA) should be added to the vial.
Storage and Stability:Samples are stable for up to twelve months at -20°C in a manual defrost freezer after the date of receipt. After reconstitution, this protein can be aliquoted and stored at above temperature for up to three months without a significant loss of activity. Avoid repeated freeze-thaw cycles.
