Factor B which is part of the alternate pathway of the complement system is cleaved by factor D into 2 fragments: Ba and Bb. Bb, a serine protease, then combines with complement factor 3b to generate the C3 or C5 convertase. It has also been implicated in proliferation and differentiation of preactivated B-lymphocytes, rapid spreading of peripheral blood monocytes, stimulation of lymphocyte blastogenesis and lysis of erythrocytes. Ba inhibits the proliferation of preactivated B-lymphocytes.
[1]"Mutations in alternative pathway complement proteins in American patients with atypical hemolytic uremic syndrome."Maga T.K., Nishimura C.J., Weaver A.E., Frees K.L., Smith R.J.H.Hum. Mutat. 31:E1445-E1460(2010). [2]"Gain-of-function mutations in com
