CR2
Binds cleavage products of C3b (C3d > C3dg > iC3b)
CR3 = MAC1
Binds iC3b fragment and recruits leukocytes by binding ICAM-1
CR1
Binds C3b and C4b
C1 Inhibitor
c1r, c1s
Factor I
C4b, C3b
Factor H
C3b (displaces Bb, alternative pathway)
MCP
C3b, C4b
Delay accelerating factor
C4b2a, C3bBb (C3 convertases - classical and alternative pathways)
C3d
Binds CR2 (CD21) - increases B cell activation