Pregnancy-associated plasma protein-A2 (PAPP-A2), a novel insulin-like growth factor-binding protein-5 proteinase.
A novel metalloproteinase with similarity to pregnancy-associated plasma protein-A (PAPP-A), which we denoted PAPP-A2, has been identified. Through expression in mammalian cells we showed that recombinant PAPP-A2 polypeptide of 1558 residues resulted from processing of a 1791-residue prepro-protein. Unlike PAPP-A, PAPP-A2 migrated as a monomer (of 220 kDa) in non-reducing SDS-polyacrylamide gel electrophoresis. The prepro-parts of PAPP-A2 and PAPP-A are not homologous, but mature PAPP-A2 shares 45% of its residues with PAPP-A. Because PAPP-A specifically cleaves insulin-like growth factor-binding protein (IGFBP)-4, one of six known modulators of IGF-I and -II, we looked for a possible PAPP-A2 substrate among the members of this family. We showed that PAPP-A2 specifically cleaved IGFBP-5 at one site, between Ser-143 and Lys-144. In contrast to the cleavage of IGFBP-4 by PAPP-A that strictly requires the presence of IGF, the cleavage of IGFBP-5 by PAPP-A2 was IGF-independent. Recent data firmly establish PAPP-A and IGFBP-4 as an important functional pair in several systems. Because of its close relationship with PAPP-A, both structurally and functionally, PAPP-A2 is a likely candidate IGFBP-5 proteinase in many tissues and conditioned media where IGFBP-5 proteolysis has been reported.
Overgaard
M T
MT
Department of Molecular and Structural Biology, Science Park, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark.
Boldt
H B
HB
Laursen
L S
LS
Sottrup-Jensen
L
L
Conover
C A
CA
Oxvig
C
C
D000595:Amino Acid Sequence; D017931:DNA Primers; D016208:Databases, Factual; D010450:Endopeptidases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D004792:Enzyme Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020224:Expressed Sequence Tags; D006801:Humans; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000378:metabolism; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011257:Pregnancy Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011266:Pregnancy-Associated Plasma Protein-A / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D004792:Enzyme Precursors; D018974:Insulin-Like Growth Factor Binding Protein 4; D011257:Pregnancy Proteins; D011994:Recombinant Proteins; D010450:Endopeptidases; C430889:PAPPA2 protein, human; D008666:Metalloendopeptidases; D011266:Pregnancy-Associated Plasma Protein-A