CFHR4

Background

The human complement factor H (CFH) protein family is composed of glycoproteins encoded by six tandem genes in the regulation of complement activation (RCA) gene cluster. These functional proteins include CFH, CFH-like protein 1 (FHL-1), and complement factor H-related proteins (CFHR1-5), among which FHL-1 is a variant of CFH by alternative splicing, while CFHR1-5 are homologous to CFH in varying degrees.

Complement factor H-related protein 4 (CFHR4) is a plasma glycoprotein with two splice variants, CFHR4A and CFHR4B. CFHR4A contains 9 short consensus repeat (SCR) domains, in which SCR1-4 are highly identical to SCR5-8. CFHR4B consists of 5 SCRs, in which SCR2-5 share 100% amino acid homology to SCR6-9 of CFHR4A, and SCR1 is 98% identical to SCR1 of CFHR4A. Similar to CFHR3, both CFHR4A and CFHR4B lack the N-terminal dimerization domain. It is challenging to detect CFHR4B concentration in plasma or serum since that FHR4B domains are practically identical to that of CFHR4A, making it difficult to prepare FHR4B-specific antibodies.

CFHR4 functions as a cofactor for CFH to regulate complement activity. By binding to the complement C3b, CFHR4 serves as a platform for the assembly of C3 convertase to activate the complement alternative pathway. And, another novel ligand C-reactive protein (CRP) has been identified recently, by which CFHR4 recruited and facilitated the native CRP bind to necrotic cells, playing an opsonization role. CFHR4 abnormality is related to atypical hemolytic uremic syndrome and hemolytic-uremic syndrome.

Fig.1 The human factor H protein family.^1,3

CFHR4 Functional Service

Creative Biolabs provides a comprehensive range of CFHR4-related products, encompassing anti-CFHR4 Antibodies, CFHR4 ELISA Assay Kits and recombinant CFHR4 Proteins. These products are designed for high specificity and sensitivity in CFHR4-related research, facilitating the study of CFHR4 expression, function, and interaction with other proteins.

Fig.2 Function of Factor H in the regulation of the complement system.^2,3

The CFHR4 functional/activity test is critical for assessing the biological activity of CFHR4 in various research contexts. Our CFHR4 function or activity testing services employ cutting-edge methods such as ELISA, Western blotting, and functional assays to quantify CFHR4's impact on immune responses, complement regulation, and its role in diseases like age-related macular degeneration and autoimmune disorders. These assays conducted with our high-quality products help determine CFHR4’s functional integrity, interactions with complement proteins, and potential for therapeutic targeting. Research has demonstrated the utility of these tests in drug development and biomarker discovery, offering new insights into CFHR4's role in immune system modulation.

Creative Biolabs provides CFHR4-functional services, including functional assays, protein analysis, custom peptide design, and activity testing. Our services assist customers in advancing CFHR4-related research with precision and expertise, providing tailored solutions for complex research needs.

References

1. Józsi, Mihály. "Factor H family proteins in complement evasion of microorganisms." Frontiers in immunology 8 (2017): 571.
2. Moore, Sara R., et al. "Hijacking factor H for complement immune evasion." Frontiers in Immunology 12 (2021): 602277.
3. Distributed under Open Access license CC BY 4.0. The image was modified by extracting and using only part of the original image.