Description
Complement C4 (C4) plays a central role in both the classical and lectin pathways of complement activation, with levels in human plasma ~0.4 mg/ml. C4 circulates in human plasma as a heterotrimer of 205 kDa in plasma, α (93 kDa), β (78 kDa), and γ (33 kDa). During complement activation, C4 is cleaved by the serine protease C1s to C4a (9 kDa) and C4b (190 kDa). C4b is further cleaved by factor I to C4d (45 kDa) and C4c (140 kDa). The current protocol yields C4c, however intact C4 and/or C4b and C4d may be co-purified