Complement factor D is a serine protease essential for the activation of the alternative pathway in the complement system. Research of complement factor D has revealed that a self inhibitory loop is responsible for switch from a resting to active state. Additionally, recent research has linked a complement factor D gene, single nucleotide polymorphism (SNP) rs3826945, with age-related macular degeneration (AMD). In these AMD cases there was a significant increase in plasma complement factor D concentration, even though previous research has shown no association between complement factor D SNP genes and AMD.
Complement factor D is a serine protease with structural homologies with chymotrypsin. In the complement cascade, factor D cleaves complement factor B in complex with activated complement component C3. It is identical to adipsin, which is expressed in adipose tissue.
