Description
Arginine residues in the terminal clotting factor fibrinogen, which is present in high concentrations in blood, can be converted to citrulline residues by peptidylarginine deiminase 4 (PAD4). Antibodies capable of recognizing citrullinated proteins, including citrulliunated fibrinogen, are found in the majority of patients with rheumatoid arthritis (RA). Immunization of mice with PAD4-citrullinated human fibrinogen has been reported to induce an arthritis that resembles human RA