CO8A is a component of the membrane attack complex (MAC), a multiprotein complex activated by the complement cascade. The MAC inserts into target cell membranes to form pores, leading to cell lysis. C8A works together with C8B and C8G to insert into the target membrane (though it doesn’t form pores by itself). During MAC assembly, it associates with C5b, C6, and C7 to form the C5b8 intermediate complex that traverses the bilayer and increases membrane rigidity.
Biological Context of CO8A
- Pathways: Complement cascade, lectin-induced complement pathway
- Biological processes: Innate immune response, coagulation
- Disease associations: Complement Component 8 Deficiency Type I — mutations impair MAC formation and increase susceptibility to Neisseria meningitidis (meningitis)