 The transcribed PTX3 protein is 381 amino acids long, has a predicted molecular weight of 40,165 Da and consists of a carboxy-terminal 203 amino acid long pentraxin domain coupled with an amino-terminal 178 amino acid long domain unrelated to other known proteins.The PTX3 carboxy-terminal domain contains a canonical pentraxin signature (HxCxS/TWxS) and two conserved cysteines (Cys-210 and Cys-271), and shares 57% conserved and 17% identical amino acids with short pentraxins.The presence of an amino-linked glycosylation site in the carboxy-terminal domain at Asn-220 accounts for the higher molecular weight observed in SDS–PAGE under reducing conditions (45 kDa as opposed to the predicted 40 kDa).