Predicted to enable serine-type endopeptidase activity. Acts upstream of or within complement activation, alternative pathway. Predicted to be located in extracellular region. Is expressed in embryo and liver lobe. Human ortholog(s) of this gene implicated in several diseases, including atypical hemolytic-uremic syndrome; autoimmune disease (multiple); eye disease (multiple); glomerulonephritis (multiple); and sickle cell anemia. Orthologous to human CFB (complement factor B). [provided by Alliance of Genome Resources, Apr 2022]