The protein encoded by this gene is a member of the trypsin family of serine proteases secreted by adipocytes into the bloodstream.
The encoded protein is a component of the alternative complement pathway best known for its role in humoral suppression of infectious agents.
Finally, the encoded protein has a high level of expression in fat, suggesting a role for adipose tissue in immune system biology.
[3] Factor D is a serine protease that stimulates glucose transport for triglyceride accumulation in fats cells and inhibits lipolysis.
Factor D displays different conformations of major catalytic and substrate-binding residues typically found in the chrotrypsin family.
Other key components of Factor D are an Asp189-Arg218 salt bridge that stabilizes a self-inhibitory loop (amino acid residues 212 to 218) and His57 side chain in the non-canonical conformation.
The mode of inheritance of Factor D deficiency is autosomal recessive, and individuals with a mutation on only one allele may not experience the same susceptibility to reoccurring infections.