What is the advantage to having C3 continuously activated at

What is the advantage to having C3 continuously activated at a low level during homeostasis? Are there any disadvantages?

Solution

Continuous low level activation, called the \"tick-over\"mechanism. This low level activation helps monitor for pathoen invasions by maintaining a low level of consitutive activation. The activated Complement protein\'s fate is determined by the position of the -OH it binds and the type of hydrogen bonding that occurs. It can hydrogen bond either with water molecules in its immediate viscinity, which leads to neutralization of the protein. On the other hand, if the protein is bound to -OH of certain sugars or -NH- of amino acids, it leads to further activation of C3 and formation of membrane attack complex.