C5
Function
Activation of C5 by a C5 convertase initiates the spontaneous assembly of the late complement components, C5-C9, into the membrane attack complex. C5b has a transient binding site for C6. The C5b-C6 complex is the foundation upon which the lytic complex is assembled.
C5a anaphylatoxin
Derived from proteolytic degradation of complement C5, C5a anaphylatoxin is a mediator of local inflammatory process. Binding to the receptor C5AR1 induces a variety of responses including intracellular calcium release, contraction of smooth muscle, increased vascular permeability, and histamine release from mast cells and basophilic leukocytes. C5a is also a potent chemokine which stimulates the locomotion of polymorphonuclear leukocytes and directs their migration toward sites of inflammation.
Involvement in disease
Murine C5 deficiency is caused by a 2 base-pairs deletion resulting in frameshift and premature truncation. All C5-deficient strains contain this mutation.
Cellular localization
- Secreted
Alternative names
Hc, C5, Complement C5, Hemolytic complement