Pentraxin 2/SAP Antibody

Pentraxin 2 (also known as Serum Amyoid P Component or SAP) is a secreted glycoprotein that is a universal non-fibrillar component of amyloid deposits. Amyloid is an abnormal extracellular deposit of insoluble protein fibrils that can lead to tissue damage and disease (1‑3). Pentraxin 2 belongs to the pentraxin (pentaxin) family, whose members have a characteristic pentagonal discoid arrangement of five non-covalently bound subunits (4). Pentraxin domains contain the consensus sequence, HxCx(S/T)WxS (x = any amino acid), a lectin fold, and two calcium-binding sites (1). They bind to a variety of unrelated molecules in a calcium-dependent lectin-like manner (1, 4, 5). Pentraxin 2 and C-reactive protein (CRP) are members of the classical or short pentraxin subfamily and share 46% amino acid (aa) identity (1). Mouse Pentraxin 2 is the major acute-phase protein whose expression is dependent on complement activation, IL-6 and/or IL-1 beta, while in humans, CRP is the major acute-phase protein (2, 5, 9). Both are produced and secreted by liver hepatocytes and circulate in plasma. The 204 aa mature mouse Pentraxin 2 shares 79% aa identity with rat Pentraxin 2 and 63‑70% aa identity with human, guinea pig, golden hamster, porcine, and bovine Pentraxin 2 (2, 5). Amyloid deposits containing Pentraxin 2 are implicated in a diverse range of diseases including Alzheimer’s, prion diseases, type 2 diabetes and various systemic amyloidoses (3, 6, 7). Pentraxin 2 regulates the solubility of amyloid fibrils and protects them from degradation. In addition to its pathogenic role, Pentraxin 2 also has an important physiological function in innate immunity (8). It is an opsonin that interacts with all three types of human Fc gamma receptors that mediate neutrophil phagocytosis (8). Pentraxin 2 has been proposed to bind and sequester a variety of ligands including auto-antigens, apoptotic cells, chromatin, DNA, and micro-organisms (1‑3). Pentraxin 2 is also a normal component of basement membranes (1).