Complement Factor Bb (Bb)

Complement factor Bb is a serine protease fragment derived from complement factor B. It is a key component of the alternative pathway C3 and C5 convertases, playing a central role in amplifying the complement cascade and mediating immune responses. Bb is generated upon cleavage of factor B by factor D when factor B is bound to C3b. As a catalytic subunit, Bb is essential for cleaving C3 and C5, leading to opsonization, inflammation, and cell lysis. Elevated levels of Bb can serve as a biomarker for diseases involving dysregulated complement activity.

Other names

Factor BbCFB fragment Bb

Bb is a catalytic subunit of the C3 and C5 convertases, which cleave C3 and C5, respectively, leading to downstream complement activation. Therapeutic strategies may aim to inhibit its activity or formation to dampen excessive complement activation.