Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The protein responsible for both nucleotide pyrophosphatase (EC 3.6.1.9) and alkaline phosphodiesterase I (EC 3.1.4.1) activities was purified from MOPC 315 plasmacytoma cells. A single SDS/PAGE-purified 115-kDa protein band was used to produce a rabbit polyclonal antiserum. This antibody preparation precipitated alkaline phosphodiesterase I activity, indicating that the SDS/PAGE-purified protein was nucleotide pyrophosphatase/alkaline phosphodiesterase I. When used for Western blot analysis, the antiserum detected a 115-kDa protein as well as a 220-kDa protein band. Multiple overlapping cDNA clones were isolated from a cDNA expression library screened with this anti-nucleotide pyrophosphatase/alkaline phosphodiesterase I antiserum. Sequence analysis indicated that the isolated cDNA clones encoded PC-1, a murine plasma cell differentiation antigen. To confirm the suspected enzymatic identity of PC-1, a recombinant PC-1 fusion protein was expressed in bacteria, purified, and used to produce another rabbit polyclonal antiserum. This antiserum likewise immunoprecipitated alkaline phosphodiesterase I activity and recognized the 115-kDa and 220-kDa proteins in Western blot analyses of cell extracts. Furthermore, expression of nucleotide pyrophosphatase/alkaline phosphodiesterase I corresponded directly with mRNA and protein levels of PC-1 in cells known to express different levels of nucleotide pyrophosphatase/alkaline phosphodiesterase I activity. Finally, steroid induction of enzymatic activity was mirrored by levels of PC-1 mRNA and protein expression. Together, these data indicate that the plasma cell differentiation antigen PC-1 is a membrane-bound enzyme, nucleotide pyrophosphatase/alkaline phosphodiesterase I.
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PMID:Identification of nucleotide pyrophosphatase/alkaline phosphodiesterase I activity associated with the mouse plasma cell differentiation antigen PC-1. 164 27

The plasma cell differentiation antigen PC-1 was purified to homogeneity from rat liver membranes. Denaturing electrophoresis revealed polypeptides of 118 and 128 kDa, which were both recognized by antibodies against recombinant murine PC-1. During gel filtration PC-1 migrated as a protein of about 500 kDa, suggesting a tetrameric structure. Purified PC-1 displayed a phosphodiesterase-I/nucleotide pyrophosphatase activity that could be completely blocked by EDTA, dithiothreitol and acidic fibroblast growth factor (extrapolated Ki = 1.3 nM). Purified PC-1 was also capable of threonine autophosphorylation and of phosphorylation of histone IIa. The autophosphorylation of PC-1 was inhibited by addition of histone IIa, and it was blocked by phosphodiesterase-I inhibitors (acidic fibroblast growth factor, dithiothreitol), by nucleotides (ATP, ADP, AMP), and by vanadate. When added to autophosphorylated PC-1, these compounds caused a prompt dephosphorylation. However, the same agents did not affect the (de)phosphorylation of histone IIa, which is not a substrate for the PC-1 phosphatase. These data indicate that phosphodiesterase-I inhibitors, nucleotides and vanadate affect the (de)phosphorylation of PC-1 by stimulating the PC-1 phosphatase and/or by shielding the autophosphorylation site from the PC-1 kinase. The rate of dephosphorylation of PC-1 was independent of the dilution, suggesting an autocatalytic intramolecular process. We propose that the autophosphorylation of PC-1 serves to block its nucleotide pyrophosphatase activity when extracellular ATP becomes scarce.
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PMID:Regulation of purified hepatic PC-1 (phosphodiesterase-I/nucleotide pyrophosphatase) by threonine auto(de)phosphorylation and by binding of acidic fibroblast growth factor. 753 98

Nucleotide pyrophosphatase (EC 3.6.1.9) is a membrane enzyme purified from a number of mammalian sources that may have alkaline phosphodiesterase I (EC 3.1.4.1) activity as well. The mol. wt and subunit structure of this membrane glycoprotein are similar to that of the murine plasma cell alloantigen, PC-1. The PC-1 protein is a disulfide-bonded dimer of identical 115 kDa polypeptides that is selectively expressed on B lineage cells that have reached the degree of maturation associated with immunoglobulin secretion. It also has restricted expression in certain non-lymphoid tissues. In this report, we show that alkaline phosphodiesterase I activity parallels PC-1 mRNA expression in a number of B lineage cell lines at different stages of differentiation. Furthermore, we demonstrate increases in both nucleotide pyrophosphatase and alkaline phosphodiesterase I enzymatic activities in transiently transfected COS-7 cells expressing a cloned PC-1 cDNA construction. These results extend our previous immunological and correlative studies and directly ascribe an enzymatic activity to this cell surface differentiation antigen. These experiments also demonstrate that a single protein is responsible for both alkaline phosphodiesterase I and nucleotide pyrophosphatase activities.
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PMID:Expression of nucleotide pyrophosphatase and alkaline phosphodiesterase I activities of PC-1, the murine plasma cell antigen. 767 57

A human cDNA clone encoding autotaxin, a tumor cell motility-stimulating protein, reveals that this protein is an ecto/exo-enzyme with significant homology to the plasma cell membrane differentiation antigen PC-1. ATX is a 125-kDa glycoprotein, previously isolated from a human melanoma cell line (A2058), which elicits chemotactic and chemokinetic responses at picomolar to nanomolar concentrations. Affinity-purified antipeptide antibodies to the ATX peptide, ATX-102, were employed to screen an A2058 cDNA expression library made in lambda gt11. The partial cDNA sequence which was obtained was then extended by utilizing reverse transcriptase on total cellular RNA followed by polymerase chain reaction amplification. The isolated cDNA clone contained 3251 base pairs, and the mRNA message size was approximately 3.3 kilobases. The deduced amino acid sequence of autotaxin matched 30 previously sequenced peptides and comprised a protein of 915 amino acids. Data base analysis of the ATX sequence revealed a 45% amino acid identity (including 30 out of 33 cysteines) with PC-1, a pyrophosphatase/type I phosphodiesterase expressed on the surface of activated B cells and plasma cells. ATX, like PC-1, was found to hydrolyze the type I phosphodiesterase substrate p-nitrophenyl thymidine-5'-monophosphate. Autotaxin now defines a novel motility-regulating function for this class of ecto/exo-enzymes.
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PMID:cDNA cloning of the human tumor motility-stimulating protein, autotaxin, reveals a homology with phosphodiesterases. 798 64

The membrane protein plasma-cell-differentiation antigen 1 (PC-1) has been described as a phosphodiesterase-I/nucleotide pyrophosphatase and as an autophosphorylating protein kinase. It has been suggested, however, that PC-1 is not a real protein kinase and that the autophosphorylated enzyme represents a nucleotidylated derivative, which is formed on Thr238 (murine PC-1) as a catalytic intermediate during ATP hydrolysis [Belli, S.I., Mercuri, F.A., Sali, A.& Goding, J.W. (1995) Eur. J. Biochem. 228, 669-676]. We have investigated the proposed multifunctional role of PC-1 and show here that ATP hydrolysis and autophosphorylation represent two distinct catalytic reactions. The enzyme was radiolabeled when various concentrations (1-260 microM) of [alpha-32P]ATP or [alpha-32P]ADP, but not [gamma-32P]ATP, were used as substrates for the formation of the pyrophosphatase catalytic intermediate, especially in the presence of imidazole, which interferes with the hydrolysis of the nucleotidylated enzyme. In contrast, autoradiography revealed autophosphorylation only with [gamma-32P]ATP as the phosphoryl donor, and autophosphorylation has been shown to occur only at ATP concentrations below 5 microM. Autophosphorylation could also be differentiated from nucleotidylation by its higher resistance to alkaline treatment and its more basic pH optimum. An intestinal nucleotide pyrophosphatase with a structurally related catalytic site could not be autophosphorylated, which shows that autophosphorylation is not an intrinsic property of the nucleotide pyrophosphatase reaction. Autophosphorylation of PC-1 was associated with inactivation of its phosphodiesterase-I/nucleotide-pyrophosphatase activity. We propose that autophosphorylation of PC-1 on Thr238 at low ATP concentrations serves as an autoregulatory mechanism that makes Thr238 unavailable for participation in the hydrolysis of extracellular nucleotides when they become scarce.
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PMID:Threonine autophosphorylation and nucleotidylation of the hepatic membrane protein PC-1. 891 28

The presence of a nucleotide pyrophosphatase (EC 3.6.1.9) on the plasma membrane of rat C6 glioma has been demonstrated by analysis of the hydrolysis of ATP labeled in the base and in the alpha- and gamma-phosphates. The enzyme degraded ATP into AMP and PPi and, depending on the ATP concentration, accounted for approximately 50-75% of the extracellular degradation of ATP. The association of the enzyme with the plasma membrane was confirmed by ATP hydrolysis in the presence of a varying concentration of pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), a membrane-impermeable inhibitor of the enzyme. PPADS concentration above 20 microM abolished the degradation of ATP into AMP and PPi. The nucleotide pyrophosphatase has an alkaline pH optimum and a Km for ATP of 17 +/- 5 microM. The enzyme has a broad substrate specificity and hydrolyzes nucleoside triphosphates, nucleoside diphosphates, dinucleoside polyphosphates, and nucleoside monophosphate esters but is inhibited by nucleoside monophosphates, adenosine 3',5'-bisphosphate, and PPADS. The substrate specificity characterizes the enzyme as a nucleotide pyrophosphatase/phosphodiesterase I (PD-I). Immunoblotting and autoadenylylation identified the enzyme as a plasma cell differentiation antigen-related protein. Hydrolysis of ATP terminates the autophosphorylation of a nucleoside diphosphate kinase (NDPK/nm23) detected in the conditioned medium of C6 cultures. A function of the pyrophosphatase/PD-I and NDPK in the purinergic and pyrimidinergic signal transduction in C6 is discussed.
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PMID:An ecto-nucleotide pyrophosphatase is one of the main enzymes involved in the extracellular metabolism of ATP in rat C6 glioma. 993 Jul 59

We have identified in plasma membrane fractions isolated from rat hepatocarcinoma AS-30D ascites cells three glycoproteins of 125 kDa, 115 kDa and 105 kDa (gp125, gp115 and gp105) which become adenylylated using ATP as substrate, most readily in the presence of EDTA. The gp115 becomes also phosphorylated. The adenylylation of these tumor glycoproteins was much lower than that of a group of analogous adenylylatable glycoproteins (gp130, gp120-gp110 dimer and gp100) present in normal rat liver plasma membrane. The tumor glycoproteins were reversibly O-adenylylated at threonine residues, as was the case for their normal rat liver counterparts. The tumor gp115, and the gp120-gp110 dimer from normal rat liver were both isolated using either ATP-affinity chromatography and/or AMP-affinity chromatography. The gp120-gp110 dimer from normal rat liver was identified as the plasma cell differentiation antigen-1 (PC-1 protein), an ecto-5' phosphodiesterase/nucleotide-pyrophosphatase (5'-PDE/NPPase). The gp115 from tumor cells also exhibited Zn2+ stimulated 5'-PDE and NPPase activities in alkaline conditions, although it appears to be distinct from the PC-1 protein. We have determined that the gp115 is an ecto-enzyme that catalyzes the hydrolysis of extracellular ATP, since its adenylylation and phosphorylation were detected in intact cells using extracellularly added [alpha-32P]ATP or [gamma-32P]ATP, respectively, in the absence of any permeabilizing agent.
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PMID:Characterization of a new plasma membrane-associated ecto-5'-phosphodiesterase/nucleotide-pyrophosphatase from rat hepatocarcinoma AS-30D cells. 1151 84

We have identified in plasma membrane fractions isolated from rat hepatocarcinoma AS-30D ascites cells three glycoproteins of 125 kDa, 115 kDa and 105 kDa (gp125, gp115 and gp105) which become adenylylated using ATP as substrate, most readily in the presence of EDTA. The gp115 becomes also phosphorylated. The adenylylation of these tumor glycoproteins was much lower than that of a group of analogous adenylylatable glycoproteins (gp130, gp120-gp110 dimer and gp100) present in normal rat liver plasma membrane. The tumor glycoproteins were reversibly O-adenylylated at threonine residues, as was the case for their normal rat liver counterparts. The tumor gp115, and the gp120-gp110 dimer from normal rat liver were both isolated using either ATP-affinity chromatography and/or AMP-affinity chromatography. The gp120-gp110 dimer from normal rat liver was identified as the plasma cell differentiation antigen-1 (PC-1 protein), an ecto-5' phosphodiesterase/ nucleotide-pyrophosphatase (5'-PDE/NPPase). The gp115 from tumor cells also exhibited Zn2+-stimulated 5'-PDE and NPPase activities in alkaline conditions, although it appears to be distinct from the PC-1 protein. We have determined that the gp115 is an ecto-enzyme that catalyzes the hydrolysis of extracellular ATP, since its adenylylation and phosphorylation were detected in intact cells using extracellularly added [alpha-32P]ATP or [gamma-32P]ATP, respectively, in the absence of any permeabilizing agent.
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PMID:Characterization of a new plasma membrane-associated ecto-5'-phosphodiesterase/nucleotide-pyrophosphatase from rat hepatocarcinoma AS-30D cells. 1157 96

The rapid degradation of unmodified phosphodiester oligodeoxynucleotides (PO-oligos) by exo -and endonucleases limits their application as antisense constructs and requires the synthesis and use of modified oligonucleotides. Phosphorothioate analogs of oligonucleotides (PS-oligos) are much more stable against nucleolytic degradation than their unmodified counterparts, and this is one of the reasons for which they are a promising class of antisense oligonucleotides. However, PS-oligos also undergo slow hydrolysis by enzymes present in plasma. The oligonucleotide degradation proceeds mainly from the 3' -end, resulting in the formation of a typical ladder of shorter products and the release of the mononucleoside 5' -phosphorothioates. So far, little has been known concerning the molecular identity of the enzymes involved in the degradation of PS-oligos. We now identify the human plasma 3' -exonuclease responsible for their degradation as a soluble form of nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) (EC 3.1.4.1/EC 3.6.1.9), also known as the plasma cell differentiation antigen PC-1. We also show that adenosine or deoxyadenosine (alpha-thio)triphosphates can act as potent inhibitors of NPPs.
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PMID:Nucleotide pyrophosphatase/phosphodiesterase 1 is responsible for degradation of antisense phosphorothioate oligonucleotides. 1746 70