Complement component 7

Complement Component 7 (C7) is a protein that plays a crucial role in the immune system, specifically in the complement system, which is a part of the innate immune response. C7 is involved in the formation of the Membrane Attack Complex (MAC), a structure that creates pores in the membranes of target cells, leading to their lysis and death. This process is essential for the defense against pathogens such as bacteria and viruses.

Structure and Function

C7 is a glycoprotein composed of several domains that allow it to interact with other components of the complement system. Its activation and function are tightly regulated to prevent damage to host cells. Upon activation, C7 binds to the C5bC6 complex on the surface of the target cell. This binding is a critical step in the assembly of the MAC, as it allows the recruitment of C8 and multiple C9 molecules, leading to the formation of the pore.

Genetics

The gene encoding C7 is located on human chromosome 5. Mutations in this gene can lead to deficiencies in the complement system, which may result in increased susceptibility to infections and possibly autoimmune diseases.

Clinical Significance

Deficiencies in C7 can lead to a condition known as complement deficiency, which is characterized by an increased susceptibility to bacterial infections, particularly Neisseria meningitidis, which can cause meningitis and sepsis. Diagnosis of C7 deficiency involves measuring the levels of complement proteins in the blood and assessing the functional activity of the complement system.

Treatment for complement deficiencies may include antibiotics to prevent infections and, in some cases, complement protein replacement therapy. Research is ongoing to develop more targeted therapies for complement-related diseases.

See Also

• Complement System
• Membrane Attack Complex
• Complement Deficiency
• Innate Immune System