C3a Protein

Natural human C3a is prepared by cleavage of human C3 protein by a human C3 convertase. C3a is a member of the anaphylatoxin family of three proteins (C3a, C4a and C5a) produced by the activation of complement. It is an unglycosylated polypeptide containing 77 amino acids with a molecular mass of 9,089 daltons. Many of the biological functions of C3a are similar to those of C5a, but C3a is approximately 10- to 20-fold less active per microgram than C5a. C3a mediates many inflammatory responses including smooth muscle contraction, vasodilation, increased vascular permeability, and release of histamine from mast cells and basophils.