Final answer:
Complement proteins on membranes are regulated through post-translational modifications, representing a form of post-translational regulation in immune response.
Step-by-step explanation:
The relative instability of complement proteins on membranes can be regarded as a form of post-translational regulation of its activity. Complement proteins are part of the complement system, which plays a crucial role in the immune response by creating pores in the membrane of invading pathogens leading to their destruction. The regulation occurs through various mechanisms, including the proteolytic cleavage of complement proteins, binding of regulatory proteins that inhibit their activation, and physical constraints imposed by the cell's cytoskeleton that limit their mobility and activity, fundamental for preventing damage to host cells.