– Complement factor H-related protein 3 is a protein that in humans is encoded by the CFHR3 gene. It is a secreted protein that belongs to the complement factor H protein family. Members of the H-related protein family are exclusively composed of individually folded protein domains. CFHR3 is synthesized as a 330 amino acid precursor that contains an 18 amino acid signal peptide and a 312 amino acid mature chain. Human CFCR3 protein might be involved in complement regulation.