Human Pappalysin‑2/PAPP‑A2 Alexa Fluor™ Plus 488‑conjugated Antibody

Pappalysins belong to a fifth family of metzincins that consists of ADAMs/ADAMTSs, MMPs, astacins and serrylysins (1, 2). PAPP-A is an important pregnancy protein and increases in plasma by a factor of about 150 during pregnancy as compared to the nonpregnant state. PAPP-A is also a major marker of Down syndrome in the first trimester of pregnancy because maternal serum levels of PAPP-A are significantly reduced when a fetus affected by Down syndrome is present (3). PAPP-A cleaves Insulin-like Growth Factor-Binding Protein-4 and -5 (IGFBP-4 and -5) at a single site, resulting in the release of bioactive IGF (4). Compared to PAPP‑A, PAPP-A2 (also called PAPP-E), the second member of the family is less characterized. PAPP-A2 shares 45% amino acid identity to PAPP-A in the mature form, which is synthesized as a preproprotein consisting of multiple domains (1). The prepro region (residues 1‑233) and the C-terminal region (residues 1397‑1791) are not included in recombinant human PAPP-A2. As an active protease, recombinant human PAPP-A2 cleaves IGFBP-5.