C3 protein

C3 protein

C3 protein is a central molecule in the complement system that plays a pivotal role in how this defense network works. When C3 is split into two pieces, one piece helps attract and activate immune cells while the other sticks to surfaces like bacteria or damaged cells, marking them for removal. That marking makes it much easier for white blood cells to recognize and eat the invaders, a process called opsonization. The splitting of C3 is a key step that amplifies the complement response, so activating C3 can quickly scale up the immune attack. Because it sits at a crossroads of different activation routes, problems with C3 can strongly affect how well the whole system functions. Too little C3 activity can lead to repeated infections, while too much or misplaced activity can cause inflammation and damage to healthy tissue. Levels and activity of C3 are sometimes measured in medical tests to help diagnose immune disorders or monitor disease activity. Because of its central importance, C3 is also a target for new drugs designed to dial down harmful complement activity in certain diseases.