Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A placenta protein, originally termed PP4, was found to inhibit the aPTT in a concentration-dependent manner. PP4 which turned out to be identical with a vascular anticoagulant of the annexin type, inhibits the blood clotting process by binding of the essential lipids in a reaction which is dependent on calcium ions. Also in the presence of calcium PP4 combines with platelet membranes neutralizing their procoagulant effect. By fluorescence-microscopy binding of PP4 to stimulated macrophages is shown. The antithrombotic effect of PP4 is demonstrated by means of thrombelastography of human blood. Coagulation triggered by the addition of thromboplastin/lipid-mixtures is extinguished by PP4.
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PMID:Anticoagulant properties of placenta protein 4 (annexin V). 208 57

Isolation of six calcium-binding proteins from human placenta is described by means of hydrophobic chromatography, calcium-dependent adsorption to heparin-Sepharose and ion-exchange chromatography. These proteins were characterized and identified as PP4, PP4-X, PAP III, p68 and lipocortins I and II belonging to the family of annexins. Antibodies raised against PP4, PAP III and p68 revealed to be highly specific, while those raised against PP4-X reacted with all investigated annexins, except PP4. Cross-reactivity was also observed between lipocortins I and II. All annexins inhibited in a concentration-dependent manner blood coagulation but with different potencies as was determined by means of a modified thromboplastin time test. The most potent inhibitors turned out to be PP4 and PAP III, followed by PP4-X, lipocortin I, p68 and lipocortin II.
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PMID:Purification and characterization of six annexins from human placenta. 214 74

The human placental proteins PP4 and PP4-X, belonging to the annexin protein family, were expressed in Escherichia coli at high yield. The proteins were purified to homogeneity. The physicochemical parameters of the recombinant proteins were determined and compared with those of their natural placental counterparts. Except for a minor change in the pI, the proteins appeared to be indistinguishable by several criteria. Both recombinant PP4 and recombinant PP4-X were biologically active in a thromboplastin inhibition test and in a phospholipase A2 inhibition test.
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PMID:Annexin proteins PP4 and PP4-X. Comparative characterization of biological activities of placental and recombinant proteins. 214 60

The placental protein PP41,2 was shown to have thromboplastin-inhibitor activity. We used partial amino acid sequence information from PP4 cyanogen bromide fragments to design oligonucleotide probes for the screening of a human placental cDNA library. In addition to the PP4 cDNA we isolated a cDNA coding for a protein with considerable homology which we subsequently termed PP4-X. PP4 and PP4-X belong to the phospholipase A2 inhibitor family, as judged by their homology to lipocortin I and calpactin I3. The full-length PP4-X cDNA encodes a protein of 321 amino acid residues including a fourfold repeat structure. Northern blot analysis using the PP4-X cDNA reveals two hybridizing RNA species of approximately 1400 nucleotides and 2500 nucleotides, respectively. The shorter one could well represent the PP4-X transcript which is in good agreement with the isolated cDNA insert of 1326 nucleotides. Expression of the PP4-X coding sequence in E. coli resulted in the appearance of a protein which crossreacts with antibodies raised against PP4.
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PMID:Isolation and expression of cDNA coding for a new member of the phospholipase A2 inhibitor family. 297 Feb 57

It has long been known that water extracts of placenta hominis (Jahage in Korean) are effective for treating immunological and vascular diseases and is a major constituent of traditional oriental medicines. We report herein on the isolation and purification of a new type of anticoagulant protein, PP27, from human placenta. PP27 ran as a single band on SDS-PAGE with a molecular mass (Mr) of 27 kDa under denaturing conditions and chromatography on a calibrated Sepharose 4B column indicated a molecular mass of 23 kDa, a value that is similar to those of other PP4 enzymes reported to date. The isoelectric point of PP27 was pI 5.2. PP27, at doses higher than 10 microg/ml, inhibited platelet activating factor (PAF)-induced platelet activation in a dose-dependent manner. The protein was found to inhibit the coagulation time in a concentration-dependent manner. PP27, which acts as a vascular anticoagulant of annexin type, inhibits the blood clotting process by virtue of its binding of essential lipids, which is dependent on the presence of Ca2+ ions. In the presence of Ca2+ ions, PP27 combines with platelet membranes and neutralizes their procoagulant effect. Coagulation, triggered by the addition of thromboplastin/lipid mixtures, is extinguished by PP27.
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PMID:Purification and characterization of a new anticoagulant protein, PP27, from placenta. 1612 55