When the C one complex binds onto the antibody antigen complex, it basically is activated. And then the C one S portion, these two proteins here basically go on and they cleave the C two and the C four proteins also part of the classical pathway. So we cleave the C two into C two a and C two b. And we cleave the C four into C four a and C four B. Now, C two A and C four A basically diffuse away. They swim away while C two B and C four B create a non covalent bond and they form a complex known as C four B C two B complex.