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

The cGMP phosphodiesterase of vertebrate retinal rod outer segments plays a key role in visual transduction. A functionally active form of the inhibitory gamma subunit of the phosphodiesterase, which keeps the enzyme inactive in the dark, has been obtained in high yield from a synthetic gene expressed in Escherichia coli. A DNA sequence encoding the 87-residue bovine gamma subunit was chemically synthesized and assembled from 10 oligonucleotides. The synthetic gene was cloned into an expression vector that uses the promoter PL of lambda phage. E. coli was transformed with this vector, which encodes a fusion protein consisting of the first 31 residues of the lambda cII protein, a 7-residue joining sequence that is specifically cleaved at its C-terminal end by clotting protease factor Xa, and the 87-residue gamma subunit. The fusion protein was solubilized in 6 M urea and purified by ion-exchange chromatography on a CM-Sephadex column. The typical yield was 1 mg of fusion protein per liter of bacterial culture, which corresponds to the amount of gamma in about 2500 bovine retinas. Proteolytic cleavage of the fusion protein by factor Xa released a synthetic gamma with the same amino acid sequence as that of native gamma. Both fusion protein and synthetic gamma inhibited trypsin-activated phosphodiesterase with high affinity (Kd less than 100 pM). Likewise, both were as effective as native gamma in inhibiting transducin-activated phosphodiesterase in rod outer segment membranes. This inhibition was reversed by the activation of additional transducin. Thus, the N terminus of gamma is not intimately involved in interactions with either the catalytic subunits of the phosphodiesterase or the activated form of transducin. In contrast, a C-terminal deletion mutant terminating at residue 74 of gamma stimulated rather than inhibited the trypsin-activated enzyme. Thus, the C-terminal region of gamma is critical for inhibition of the phosphodiesterase.
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PMID:Expression in bacteria of functional inhibitory subunit of retinal rod cGMP phosphodiesterase. 254 82

We studied the effect on both platelet aggregation and blood coagulation, known to be major risk factors in thrombogenesis, of proteins from hen egg yolk (EP). EP potently inhibited collagen-induced human platelet aggregation in a dose-dependent manner. Furthermore, EP has a synergistic effect on the inhibition of human platelet aggregation with both molsidomine, an inhibitor of cGMP-specific phosphodiesterase, and theophylline, an inhibitor of cAMP-specific phosphodiesterase. These results indicate that the active mode of EP might be involved in elevation of the levels of both cGMP and cAMP. Prothrombin time and activated partial thromboplastin time were potently prolonged by EP. These data suggest that EP prolongs the time interval between the conversion of fibrinogen to fibrin. Accordingly, these findings demonstrate that EP might have antithrombotic effects by inhibiting platelet aggregation and fibrin formation.
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PMID:Effects of proteins from hen egg yolk on human platelet aggregation and blood coagulation. 1451 41