title: Inhibition of phosphodiesterase/pyrophosphatase activity of PC-1 by its association with glycosaminoglycans.
abstract: PC-1 is a type II membrane-bound glycoprotein consisting of a short N-terminal cytoplasmic domain and a large C-terminal extracellular domain, which contains phosphodiesterase/pyrophosphatase activity. When Jurkat T cells were cultured with dibutyryl cAMP, the membrane-bound PC-1 and its soluble form were induced. They were purified as a homodimer of a 130 kDa peptide and a 120 kDa monomer, respectively, and the same two forms could also be obtained from COS-7 cells that had been transfected with PC-1 cDNA. The membrane-bound and soluble forms of PC-1 were indistinguishable from each other in terms of their enzyme kinetics and N-glycosylated moieties. Thus, the enzymatically active and fully glycosylated form of soluble PC-1 was utilized to search for its interacting molecules. The phosphodiesterase/pyrophosphatase activity of PC-1 was competitively inhibited by glycosaminoglycans, such as heparin and heparan sulfate, which are the major components of the extracellular matrix. PC-1 was capable of binding to heparin-Sepharose and the binding was inhibited in the presence of the enzyme substrate, ATP or its nonhydrolyzable analog. The enzyme activity of PC-1 itself, however, was not required for the binding to heparin-Sepharose. These results suggest that PC-1 might function as an adhesion molecule independent of its enzyme activity to associate with glycosaminoglycans in the extracellular matrix.
authors.affiliation: Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Hosoda
authors.forename: S I
authors.initials: SI
authors.lastname: Hoshino
authors.forename: Y
authors.initials: Y
authors.lastname: Kanda
authors.forename: T
authors.initials: T
authors.lastname: Katada
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D019556:COS Cells; D015815:Cell Adhesion Molecules / Q000378:metabolism; D004791:Enzyme Inhibitors; D004800:Enzymes, Immobilized; D005109:Extracellular Matrix / Q000378:metabolism; D006025:Glycosaminoglycans / Q000494:pharmacology*; D006031:Glycosylation; D006493:Heparin / Q000494:pharmacology; D006497:Heparan Sulfate / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors*; D012685:Sepharose / Q000031:analogs & derivatives / Q000378:metabolism; D012995:Solubility; D014162:Transfection
chemical_list: D003994:Bucladesine; D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D004800:Enzymes, Immobilized; D006025:Glycosaminoglycans; D006493:Heparin; D006497:Heparan Sulfate; D008562:Membrane Glycoproteins; D010727:Phosphoric Diester Hydrolases; D020033:Protein Isoforms; D011755:Pyrophosphatases; D012685:Sepharose; C037405:heparin-sepharose; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1