C1QB

Background

Human complement C1q subcomponent subunit B (C1QB) is a 25 kDa polypeptide chain with 253 amino acids. Similar to C1QA, C1QB consists of a collagen-like ‘stalk’ at the N terminus and a globular ‘head’ at the C terminal. Human complement C1q is a protein complex composed of six heterotrimers, each of which contains a C1QA, a C1QB, and a C1QC chain. Each heterotrimer is noncovalently linked to each other, and in the heterotrimer, there are three polypeptide chains are connected by disulfide bonds. Thus, the C-terminal portion of these chains in each heterotrimer form the globular ‘head’ of complement C1q (gC1q), and the N- terminal sequences form the collagen-like region of complement C1q (cC1q).

As a critical component of complement C1q, C1QB expression is directly related to the function of C1q and complement classical pathway activation. Diseases associated with C1QB abnormity mainly include C1q deficiency, autoimmune diseases, immunodeficiency, and Alzheimer’s disease.

Fig.1 C1QB subunit architecture and assembly.^{1, 3}

C1QB Functional Service

Creative Biolabs provides a comprehensive collection of products tailored to C1QB, including anti-C1QB antibodies, ELISA kits, recombinant C1QB proteins, and reporter vectors embedded with C1QB clones. These precisely engineered reagents are essential for dissecting the interactions of C1QB proteins with diverse molecular entities, thereby facilitating research initiatives aimed at devising therapeutic approaches for numerous diseases.

Fig.2 Distribution patterns of zebrafish c1qA, c1qB, and c1qC across tissues.^{2, 3}

C1q proteins are fundamental elements of the classical complement pathway, with well-established roles in humans and mammals, yet their characteristics in fish remain underexplored. Researchers successfully cloned full-length cDNAs of zebrafish c1qA, c1qB, and c1qC, highlighting the chromosomal synteny’s conservation across species. Expressed as soluble proteins in Escherichia coli, the globular heads of C1QA, C1QB, and C1QC were functionally analyzed. Hemolytic assays indicated that zebrafish anti-C1q antibodies could significantly inhibit hemolytic activity in carp serum. These findings suggest a conserved classical pathway function from fish to humans, with zebrafish C1qs binding specifically to aggregated IgM and IgG molecules.

Creative Biolabs provides a comprehensive suite of services centered on C1QB function, including assays for C1QB binding and a variety of specialized functional evaluations. These services are meticulously tailored to assist our distinguished clients in advancing their clinical and research objectives.