Factor Ba Protein

Factor Ba is the fragment of complement factor B that results from activation of the alternative pathway. The factor Ba fragment from factor B which was purified from normal human serum. Complement factor B is a glycosylated protein composed of a single 93,000 Da polypeptide chain. Factor B is an essential component of the alternative pathway of complement activation and is found in plasma at approximately 200 μg/mL. In the presence of Mg++ factor B binds to C3b and the C3bB complex can be activated by factor D, a serine protease that circulates as an active trypsin-like serine protease. Cleavage of factor B by factor D causes the release of the Ba fragment (33,000 Da) and leaves the 60,000 Da Bb fragment bound to C3b.