The function of PAPPA (pappalysin 1, ENSG00000182752) is as follows. 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. {ECO:0000269|PubMed:10077652, ECO:0000269|PubMed:10913121, ECO:0000269|PubMed:11522292}.