The polyclonal antibody reacts with Rat C4. Rat complement factor C4, formerly known as Gg protein, consists of an alpha-, beta-, and gamma-chain. The classical pathway of complement and the Mannose binding lectin activation pathway converge at C4. C1s, MASP-1 and MASP-2 cleave C4 resulting in the formation of C4a and C4b. The latter can be cleaved to result in C4c and C4d, in which step all functional sites are lost.