Pregnancy-associated plasma protein A (PAPP-A) is a metallo-protease belonging to Merops family M43. It cleaves insulin-like growth factor (IGF) binding protein-4 (IGFBP-4), causing a dramatic reduction in its affinity for IGF-I and -II. Through this mechanism, PAPP-A is a regulator of IGF bioactivity in several systems, including the human ovary and the cardiovascular system.

1: Molecular regulation of the IGF-binding protein-4 protease system in human fibroblasts: identification of a novel inducible inhibitor. Chen BK, Overgaard MT, Bale LK, Resch ZT, Christiansen M, Oxvig C, Conover CA; Endocrinology 2002;143:1199-1205. PMID:11897673

2: Pregnancy-associated plasma protein-A (PAPP-A) in ovine, bovine, porcine, and equine ovarian follicles: involvement in IGF binding protein-4 proteolytic degradation and mRNA expression during follicular development. Mazerbourg S, Overgaard MT, Oxvig C, Christiansen M, Conover CA, Laurendeau I, Vidaud M, Tosser-Klopp G, Zapf J, Monget P; Endocrinology 2001;142:5243-5253. PMID:11713222

3: Characterization of the enzymatic specificity of the IGF-dependent insulin-like growth factor binding protein-4 (IGFBP-4) protease. Chelius D, Conover CA, Baldwin MA, Spencer EM; Growth Horm IGF Res 2000;10:360-366. PMID:11161967

4: Expression of recombinant human pregnancy-associated plasma protein-A and identification of the proform of eosinophil major basic protein as its physiological inhibitor. Overgaard MT, Haaning J, Boldt HB, Olsen IM, Laursen LS, Christiansen M, Gleich GJ, Sottrup-Jensen L, Conover CA, Oxvig C; J Biol Chem 2000;275:31128-31133. PMID:10913121