Which component is crucial for the formation of the membrane attack complex in the complement system?

The formation of the membrane attack complex (MAC) in the complement system is a key part of the immune response that enables the body to effectively target and lyse pathogens. C5 is particularly crucial in this process because it is the component that is cleaved to generate C5a and C5b.

C5b plays a direct role in the assembly of the MAC. Once C5b is formed, it initiates a cascade that leads to the recruitment of other complement components, specifically C6, C7, C8, and several molecules of C9, ultimately leading to the formation of a pore in the membrane of the pathogen. This pore disrupts the cellular integrity of the pathogen, leading to cell lysis.

While the other components listed contribute to the overall process of complement activation and the formation of the MAC, C5 has the specific function of serving as the pivotal component that initiates the recruitment of subsequent proteins necessary for creating the membrane attack complex.