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)

Twelve acid hydrolases, 4 near-neutral hydrolases, and alkaline phosphatase were demonstrated in 0.34 M sucrose homogenates of Trypanosoma cruzi strain Y: p-nitrophenylphosphatase and alpha-naphthylphosphatase, with optimum pH at approximately 6.0; alpha=ga;actpsodase. beta=ga;actpsodase. beta=g;icpsodase, N-acetyl-beta-glucosaminidase, cathepsin A and peptidase I and III, with optimum pH between 5.0 and 6.0; and arylsulfatase, cathepsin D, alpha-arabinase and alpha-mannosidase with optimum pH at approximately 4.0. alpha-Glucosidase, glucose-6-phosphatase and peptidase II had optimum pH at approximately 7.0. beta-Glycerophosphatase had a broad pH-activity curve from 4,0 to 7.4, with maximum activity at pH 7.0. The main kinetic characteristics of these enzymes and their quantitative assay methods were studied. No activity was detected for alpha-fucosidase, beta-xylosidase, beta-glucuronidase, elaidate esterase, acid lipase, and alkaline phosphodiesterase.
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PMID:Acid and neutral hydrolases in Trypanosoma cruzi. Characterization and assay. 4 19

The gamma-subunit of retinal rod-outer-segment phosphodiesterase (PDE-gamma) is a multifunctional protein which interacts directly with both of the catalytic subunits of PDE (PDE alpha/beta) and the alpha-subunit of the retinal G (guanine-nucleotide-binding)-protein transducin alpha (T alpha). We have previously reported that the PDE gamma binds to T alpha at residue nos. 24-45 [Morrison. Rider & Takemoto (1987) FEBS Lett. 222, 266-270]. In vitro this results in inhibition of T alpha GTP/GDP exchange [Morrison, Cunnick, Oppert & Takemoto (1989) J. Biol. Chem. 264, 11671-11681]. We now report that the inhibitory region of PDE gamma for PDE alpha/beta occurs at PDE gamma residues 54-87. This binding results in inhibition of either trypsin-solubilized or membrane-bound PDE alpha/beta. PDE gamma which has been treated with carboxypeptidase Y, removing the C-terminus, does not inhibit PDE alpha/beta, but does inhibit T alpha GTP/GDP exchange. Inhibition by PDE gamma can be removed by T alpha-guanosine 5'-[gamma-thio]triphosphate (GTP[S]) addition to membranes. This results in a displacement of PDE gamma, but not in removal of this subunit from the membrane [Whalen, Bitensky & Takemoto (1990) Biochem. J. 265, 655-658]. These results suggest that low levels of T alpha-GTP[S] can result in displacement of PDE gamma from the membrane in vitro as a GTP[S]-T alpha-PDE gamma complex. Further activation by high levels of T alpha-GTP[S] occurs by displacement of PDE gamma from its inhibitory site on PDE alpha/beta, but not in removal from the membrane.
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PMID:Binding of the gamma-subunit of retinal rod-outer-segment phosphodiesterase with both transducin and the catalytic subunits of phosphodiesterase. 217 4

We find prompt, high stoichiometry phosphorylation of rhodopsin in response to low fractional rhodopsin bleaching in bovine rod outer segments (ROS). For example, 4 +/- 1 phosphates are incorporated per bleached rhodopsin (Rho*) in 30 sec and 6 +/- 2 phosphates are incorporated in 75 sec in response to bleaching 1% of the rhodopsin in the presence of 1 mM [gamma-32P]ATP and 0.1 mM nonradioactive GTP. Omission of GTP leads to ca 70% inhibition of rhodopsin phosphorylation, presumably due to the GTP-binding protein blocking access of rhodopsin kinase to rhodopsin. Light induced phosphodiesterase (PDE) activation is rapidly quenched in the presence of ATP as first reported by by Liebman and Pugh [Nature 287, 734-736 (1980)]. The kinetics of rhodopsin phosphorylation vary with conditions and from preparation to preparation, however, they are always at least as fast as the ATP dependent quenching of PDE activation. The maximum extent of rhodopsin phosphorylation was limited by specific proteolytic trimming of the carboxyl-terminal phosphorylation sites in washed ROS membranes "stripped" of extrinsic proteins. Membrane preparations with 6,4,2, or 1 phosphate(s) incorporated/Rho* (after a 75 sec post bleach incubation) were produced by treatment with: no protease, carboxypeptidase Y (C), trypsin (T), or both T and C (TC), respectively, followed by reassociation with extrinsic membrane proteins and phosphorylation. Low fractional bleaching was required for maximum phosphorylation/Rho* in membranes which were stripped and reassociated with extrinsic proteins and in isolated ROS. Removal of C-terminal rhodopsin phosphorylation sites has little or no effect on light activation of PDE in the absence of ATP. However, in the presence of ATP the extent of the removal of C-terminal rhodopsin residues has large effects on the light activation and the shut-off of PDE. The single phosphate/Rho* that was added to TC digested membranes reduced the lifetime of Rho* but apparently was not incorporated rapidly enough under our conditions to inhibit the Vmax of PDE. The two phosphates/Rho* which were incorporated after T digestion cause a large decrease in the lifetime of Rho* as well as a decrease in the Vmax of PDE (at low bleaching levels). The four phosphates/Rho* that were added after C digestion further reduce the lifetime of Rho* and the Vmax of PDE. The 6 phosphates/Rho* which were incorporated into the unproteolyzed membranes have little additional effect on Rho* lifetime compared to 4 phosphates/Rho*. However, increasing the phosphorylation observed from 4 to 6 phosphates greatly inhibits the Vmax of PDE at intermediate bleaching levels.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Phosphorylation at sites near rhodopsin's carboxyl-terminus regulates light initiated cGMP hydrolysis. 609 32