Pump-1 cDNA codes for a protein with characteristics similar to those of classical collagenase family members.
Pump-1 cDNA has recently been isolated by screening a human tumor cDNA library with a transin (rat stromelysin) probe under low-stringency hybridization conditions. The cDNA codes for a potential protein with significant sequence similarity to the metalloproteinases collagenase and stromelysin, but which lacks the hemopexin-like domain characteristic of these enzymes. Expression of pump-1 cDNA in cos cells using an expression vector leads to secretion of a protein of Mr 28,000 with latent, organomercurial-activatable proteinase activity. Cos cells transfected with a partial pump-1 cDNA in the vector pPROTA secrete a fusion protein between the IgG-binding domains of staphylococcal protein A and pump-1. The fusion protein binds to IgG-Sepharose, and the bound fusion protein undergoes apparent autocleavage in the presence of 4-aminophenylmercuric acetate with elution of active pump-1 species of Mr 21,000 and 19,000. Active pump-1 degrades casein, gelatins of types I, III, IV, and V, and fibronectin and can activate collagenase. Active pump-1 is inhibited by EDTA, 1,10-phenanthroline, and the tissue inhibitor of metalloproteinases. These results show that, despite the absence of a hemopexin-like domain, pump-1 is a latent secreted metalloproteinase. Postpartum rat uteri contain elevated levels of rat pump-1 mRNA. On the basis of this observation, its size, and its substrate specificity, we suggest that pump-1 might correspond to a previously described uterine metalloproteinase, matrix metalloproteinase 7.
Quantin
B
B
Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Strasbourg, France.
Murphy
G
G
Breathnach
R
R
D000595:Amino Acid Sequence; D000818:Animals; D004273:DNA, Neoplasm / Q000235:genetics*; D005796:Genes; D005822:Genetic Vectors; D005914:Globins / Q000235:genetics; D006801:Humans; D007700:Kinetics; D020783:Matrix Metalloproteinase 7; D008666:Metalloendopeptidases / Q000235:genetics* / Q000378:metabolism; D003012:Microbial Collagenase / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D005810:Multigene Family; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
D004273:DNA, Neoplasm; D011993:Recombinant Fusion Proteins; D005914:Globins; D008666:Metalloendopeptidases; C060932:MMP7 protein, human; D020783:Matrix Metalloproteinase 7; D003012:Microbial Collagenase