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PAPPA

Developmental stage

Present in serum and placenta during pregnancy; levels increase throughout pregnancy.

Function

Metalloproteinase which specifically cleaves IGFBP-4 and IGFBP-5, resulting in release of bound IGF. Cleavage of IGFBP-4 is dramatically enhanced by the presence of IGF, whereas cleavage of IGFBP-5 is slightly inhibited by the presence of IGF.

Post-translational modifications

There appear to be no free sulfhydryl groups.

Sequence similarities

Belongs to the peptidase M43B family.

Tissue specificity

High levels in placenta and pregnancy serum. In placenta, expressed in X cells in septa and anchoring villi, and in syncytiotrophoblasts in the chorionic villi. Lower levels are found in a variety of other tissues including kidney, myometrium, endometrium, ovaries, breast, prostate, bone marrow, colon, fibroblasts and osteoblasts.

Cellular localization

  • Secreted

Alternative names

  • Pappalysin-1
  • Insulin-like growth factor-dependent IGF-binding protein 4 protease
  • Pregnancy-associated plasma protein A
  • IGF-dependent IGFBP-4 protease
  • IGFBP-4ase
  • PAPP-A
  • PAPPA

Target type

Proteins

Molecular weight

180973Da