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Human C1q Protein, Natural - 1 mg (CAT#: CB-P272-AB) Datasheet

Product Type
The complement system plays an important role in both innate and adaptive immune responses, and can produce inflammatory and protective responses to pathogen attacks before the adaptive response occurs. There are three ways to activate complement. The classical pathway is triggered by immune complexes. Surface-bound mannan-bound lectin pathways; and all surfaces that are not specifically protected. Each produces C3 convertase, a serine protease that cleaves the central complement protein C3 and produces the main cleavage fragment C3b. C3 and C5 invertases are enzyme complexes that initiate and amplify the activity of the complement pathway and ultimately produce cytolytic MAC. C1q together with C1r and C1s form the first part of the classical complement pathway, C1 macromolecules. C1q is a complex composed of 18 polypeptide chains of three different types (A, B, C; 29, 27, 23 kDa respectively). The interaction between the immune complex and C1q induces conformational changes in the C1 complex, thereby activating the classical pathway. C1q acts as a recognition unit by binding to the heavy chain of IgG or IgM (Fcγ and Fc micro), provided that the immunoglobulin binds to its antigen. In addition, C1q can also recognize molecular patterns associated with pathogens, and can bind to apoptotic vesicles, thereby activating the classical complement pathway and mediating phagocytosis. C1q is mainly produced by macrophages, but also by follicular dendritic cells, finger cells and cells of the mononuclear macrophage lineage. C1q deficiency has a profound impact on host defense and immune complex clearance. Lack of C1q may lead to impaired clearance rate of apoptotic cells, leading to autoimmunity. Hereditary C1q deficiency is also associated with the development of systemic lupus erythematosus (SLE). In addition, recent studies have shown that C1q is involved in non-complement cell processes, including new blood vessel formation during pregnancy, blood coagulation, tissue repair, cancer and the function of nerve synapses.
1 mg
PBS, pH 7.4
Functional studies, Immuno assays, Western blot
Application Notes
The use of diluent depends on the detection system used. It is recommended that users test reagents and determine their own optimal dilution.
W: Reduce sample handling and use SDS-Page. The band size is approximately 150 kDa.
FS: Complement activation after incubation with CVF is tested by lysis of sheep red blood cells.
Storage Instructions
Product should be stored at -80°C. Repeated freeze and thaw cycles will cause loss of activity. Use C5 protein within 25 hours after thawing and keep on ice. Remainder amounts should be aliquoted and immediately re-freezed for future use. Aliquots should never be thawed more than once. Under recommended storage conditions, product is stable for at least one year.
Alternative Names
11S protein

All products and services are for Research Use Only. Do Not use in humans.


Creative Biolabs has established a team of customer support scientists ready to discuss ADCC/CDC optimization strategies, antibody production, bioinformatics analysis and other molecular biology/biotechnology issues.

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