C7

Definition

C7, or complement component 7, is a protein that plays a crucial role in the complement system, which is part of the immune response. It acts as an intermediary in the formation of the membrane attack complex (MAC), helping to lyse pathogens such as bacteria and infected cells. Understanding C7's function is essential for grasping how the complement system contributes to innate immunity and enhances the ability of antibodies and phagocytic cells to clear pathogens from an organism.

5 Must Know Facts For Your Next Test

1. C7 is essential for the assembly of the membrane attack complex, which includes other complement proteins like C5, C6, and C8.
2. Deficiencies in C7 can lead to increased susceptibility to infections, particularly with Neisseria species, due to the compromised ability to form MAC.
3. C7 binds to C5b and C6 to facilitate their interaction with C8, which is critical for forming the pore structure of MAC.
4. The function of C7 is influenced by its cleavage by proteolytic enzymes during complement activation, which triggers its activity.
5. Studies on C7 have implications for understanding certain autoimmune diseases and therapies targeting the complement system.

Review Questions

• How does C7 contribute to the formation of the membrane attack complex and its role in immune defense?
  • C7 is a vital component in the formation of the membrane attack complex (MAC), which targets and destroys pathogens. When complement activation occurs, C5b binds to C6 and then recruits C7, allowing these components to interact with C8 and subsequently C9. This assembly results in a pore-forming structure that disrupts the integrity of pathogen membranes, leading to cell lysis and enhanced clearance from the immune system.
• Discuss the consequences of C7 deficiency on an individual's immune response and susceptibility to infections.
  • A deficiency in C7 significantly impairs an individual's ability to effectively fight off certain infections, particularly those caused by Neisseria species. Without adequate C7 levels, the formation of the membrane attack complex is compromised, resulting in an inability to lyse these bacteria. This condition can lead to recurrent infections and emphasizes the importance of a fully functioning complement system in maintaining immune competence.
• Evaluate how understanding C7's function can inform therapeutic approaches for autoimmune diseases related to the complement system.
  • Understanding the role of C7 in complement activation allows researchers and clinicians to develop targeted therapies for autoimmune diseases that involve dysregulation of this system. For instance, inhibitors that modulate C7 activity may help restore balance in conditions where excessive complement activation leads to tissue damage. By focusing on specific components like C7, treatments can be more precisely tailored, potentially reducing side effects associated with broader immunosuppressive therapies.

Related terms

Complement System: A group of proteins that work together to opsonize pathogens, promote inflammation, and induce cell lysis.

Membrane Attack Complex (MAC): A structure formed by complement proteins that creates pores in the membranes of target cells, leading to their destruction.

Opsonization:

The process by which pathogens are marked for destruction by phagocytes through the binding of opsonins, such as complement proteins.