Western blot analysis of Complement C3a in human serum. Samples were incubated in Complement C3a monoclonal antibody (Product # MA5-47399) using a dilution of 1:3,000. 0.1 μg human C3 protein (lane 1), 10 μg normal human serum proteins (lane 2) was blotted with complement C3a. The complement C3a monoclonal binds strongly and cleanly to a band at about 115 kDa which represents the intact alpha subunit of C3 and a weaker proteolytic band at approximately 45 kDa which is the C-terminal of the alpha subunit including the netrin domain. Bands at 190 kDa and above are likely the pro-C3 and its glycosylated form.