Amino-acid and cDNA nucleotide sequence of human complement factor D. The sequence data are from White et al³³  and Biesma et al.²⁸  5′UTR indicates 5′untranslated region; first arrow (→), start of protein synthesis; second arrow, start of circulating protein sequence; asterisks, positions of catalytic triad Asp114, His66, and Ser208; arrowheads, positions of mutations; and 3′UTR, part of 3′untranslated region. A disulfide bond exists in the wild-type factor D between Cys148 and Cys214, which is indicated in bold on a gray background (gray boxes).