The clone BRA-10G binds with human CD59, a 20 kDa glycosyl phosphatidyl-inositol (GPI)-anchored cell surface protein. CD59 regulates complement-mediated cell lysis and is a potent inhibitor of the complement membrane attack complex. CD59 is widely distributed on cells in all tissues. The CD59 expression on erythrocytes is important for their survival. Genetic defects in GPI-anchor attachment, that cause a reduction or loss of CD59 and CD55 on erythrocytes produce the symptoms of the disease paroxysmal hemoglobinuria (PNH). This MAb is useful for study on GPI-anchored proteins, PNH and CD59 functions.