C1QC

C1QC, also known as the C1q C chain, is a protein that is a component of the first component of the complement system, C1. The complement system is a crucial part of the innate immune system that helps to defend the body against pathogens. C1 itself is a complex molecular machine composed of three distinct subcomponents: C1q, C1r, and C1s. C1q is the recognition unit of C1, responsible for binding to immune complexes or directly to the surface of certain pathogens. C1q is a large, flower-like protein structure made up of 18 polypeptide chains: six collagen-like chains and twelve globular heads. These twelve globular heads are arranged in six pairs, each pair being formed by one A chain and one B chain. The remaining six chains are the C chains, also known as C1QC. Each C1QC chain is linked to an A chain and a B chain, forming a C1q hexamer. The C1QC chains contribute to the structural integrity of the C1q molecule and play a role in its assembly and function. Mutations in the gene encoding C1QC can lead to deficiencies in C1q and consequently impair the classical pathway of complement activation. This impairment can increase susceptibility to certain infections, particularly those caused by encapsulated bacteria. Research into C1QC and its role in C1q function continues to shed light on the intricate mechanisms of the immune system and the development of therapeutic strategies for complement-related disorders.