sentences:  The C4 protein consists of 3 subunits (α, β, and γ) having molecular weights (MWs) of ~95,000, 78,000, and 31,000, respectively and they are all joined by interchain disulfide bridges.In a study by Roos et al., the α-chains between the C4A and C4B were found to be slightly different (MW of ~96,000 and 94,000, respectively), proving that there is actually a structural difference between the two variants.Moreover, they implicated that a lack of C4 activity could be attributed to the structural differences between the α-chains.