Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein phosphatases associated with the particulate fraction from rat liver were studied by chromatographing the fraction on a DEAE-cellulose column and assaying the eluate with phosphorylase alpha and glycogen synthase D as substrates. Phosphorylase phosphatase activity emerged as two peaks, termed P-1 and P-2 in order of elution, both of which were inhibited by Mn2+ and Mg2+. P-1 and P-2 were Mr = 50,000 and 32,000 proteins, respectively, and when treated with trypsin, P-1 converted to a form indistinguishable from P-2, to which protein phosphatase inhibitor-2 was a potent inhibitor. Thus P-2 appears to be the catalytic subunit of type-1 protein phosphatase even though it has been degrated proteolytically as evidenced by its relatively low Mr. The elution profile of glycogen synthase phosphatase activity was entirely different. The activity obtained with 5 mM Mn2+ resolved into three peaks, the second-migrating M-2 being the largest. M-2 is an Mr = 70,000 protein; but an attempt to purify it has been unsuccessful giving a product of Mr = 40,000 and closely similar to the type-1 catalytic subunit in properties including inhibition by inhibitor-2. These results suggest that phosphatases P-1 and M-2 have a common catalytic subunit (type-1), which is bound to different "regulatory" subunits. M-2 distributes in glycogen particles and microsomes evenly while P-1 is almost exclusively in microsomes.
...
PMID:Characterization of protein phosphatases associated with the particulate fraction from rat liver. 216 61

Ca2(+)-dependent protein phosphatase was purified from scallop adductor smooth muscle by a combination of DEAE-Toyoperal 650S ion exchange chromatographies and gel filtration on Sephacryl S-300. The phosphatase consisted of two subunits having molecular weights of 60 and 19 kDa. Phosphorylated regulatory light chain-a (RLC-a) was dephosphorylated by this phosphatase both in free and bound states in myosin prepared from the opaque portion of scallop smooth muscle (opaque myosin). The dephosphorylation was activated by Ca2+. The half maximal activation was a 1 microM free Ca2+ in the presence of calmodulin and 7 microM free Ca2+ in the absence of calmodulin. Opaque myosin phosphorylated at the heavy chain was not dephosphorylated with this phosphatase. p-Nitrophenyl phosphate was dephosphorylated. In addition to Ca2+, the phosphatase activity for RLC-a was activated by Mn2+, while p-nitrophenylphosphatase activity was activated by Mg2+ more strongly than by Mn2+. The pH-activity curves showed a maximum at pH 7 in the presence of Mn2+, but at around pH 8 in the presence of Mg2+. This phosphatase is similar to phosphatase 2B or calcineurin. The possible regulatory function of this phosphatase in scallop catch muscle is discussed.
...
PMID:Ca2(+)-dependent protein phosphatase which dephosphorylates regulatory light chain-a in scallop smooth muscle myosin. 216 91

We purified glucocorticoid receptors quickly but very partially using DEAE-resin. [3H]-Triamcinolone acetonide-labeled and non-activated receptors in the quickly purified fraction were found to be separated into two fractions (P-2 and P-3) by hydroxyapatite column chromatography. The P-2 receptor was the main component, and the ratio of P-2/P-3 was around 2. The molecular weights of the two receptors were calculated to be the same, 242,000: Rs = 6.2 nm and s20,w = 9.0. Treatment of the receptor with catalytic subunits of phosphoprotein phosphatase 2A1 reduced the P-2/P-3 ratio from 2 to 0.5, while treatment with catalytic subunits of cAMP-dependent protein kinase and ATP increased it to 2.5. The isolated P-3 receptor could be converted into the P-2 type by the kinase treatment. Tungstate, a phosphatase inhibitor, stabilized the P-2 receptor, and the P-2/P-3 ratio was larger than 3 when the DEAE-fraction was prepared in the presence of tungstate. However, the tungstate effect was not very strong, and the P-2 type tended to change into the P-3. [3H]-Triamcinolone acetonide-labeled and non-activated receptors were purified very highly by using an affinity gel; the procedure required more than 10 h. Only the P-3 form was observed in the preparation of highly purified receptors. Hormone-free receptors were affected by neither the phosphatase nor the kinase. The results indicate that the hormone binding makes the receptor sensitive to phosphatase. The reversibly dephosphorylated receptor is more stable than the non-dephosphorylated one, and can be activated.
...
PMID:Phosphorylated and dephosphorylated types of non-activated glucocorticoid receptor. 222 27

Human red cell cytosol acid phosphatase activity is supported by a main enzyme which can be extracted by DEAE and phosphocellulose chromatography. It uses pNPP as a substrate and is a protein phosphatase specific to phosphotyrosine. It dephosphorylates the tyrosine-phosphorylated cytosolic fragment of membrane protein 3. When taken together, these results suggest that the physiological role of red cell acid phosphatase is the FB3 phosphotyrosine dephosphorylation. Whatever it may be phosphotyrosine protein phosphatase activity is the first role of red cell acid phosphatase to be demonstrated.
...
PMID:The human red cell acid phosphatase is a phosphotyrosine protein phosphatase which dephosphorylates the membrane protein band 3. 241 29

Phosphotyrosyl-protein phosphatase activity of human erythrocyte cytosol can be resolved into two fractions by DEAE-cellulose chromatography followed by P-cellulose chromatography. Both 32P-Tyr-phosphatases are able to dephosphorylate 32P-Tyr of poly (Glu-Tyr) 4:1 but not angiotensin II and synthetic peptide Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Arg-Gly, previously phosphorylated on tyrosine residues by rat spleen tyrosine-protein kinase. Both 32P-Tyr-phosphatase activities distinctly differ from either 32P-Ser-casein phosphatase activity or "acid" and "alkaline" p-nitrophenylphosphatase activities with regard to catalytic and physico-chemical properties such as substrate specificity, chromatographic behaviour, response to various effectors.
...
PMID:Partial purification and characterization of phosphotyrosyl-protein phosphatase(s) from human erythrocyte cytosol. 242 49

Seven Tyr-protein phosphatase activities were isolated from bovine brain using phosphotyrosyl-casein as a model substrate. The activities were resolved from the cytosolic fraction by a three-step procedure employing successive DEAE-cellulose, phosphocellulose, and gel permeation chromatography steps. The seven activities accounted for 70% of the Tyr-protein phosphatase activity in bovine brain extracts and were distinct from type 1 and type 2 Ser/Thr-protein phosphatases and from the major alkaline phosphatase activities. Apparent molecular weights of the activities by gel permeation chromatography were: phosphotyrosyl-protein phosphatase (PTP)-1A (Mr 86,000), PTP-1B (Mr 24,000), PTP-2 (Mr 88,000), PTP-3 (Mr 90,000), PTP-4 (Mr 80,000), PTP-5 (Mr 48,000), and PTP-6 (Mr 104,000). PTP-5 was the major activity accounting for 26% of total while the remaining activity was divided rather evenly among the other six activities. PTP-5 was further purified to near homogeneity by additional chromatographies on Affi-Gel Blue, heparin-agarose, and Mono S giving an overall purification of 50,000-fold and a yield of 5.8%. One of two major polypeptides (Mr 46,000) in the preparation was identified as PTP-5 since it alone expressed protein phosphatase activity when protein-staining bands were eluted from sodium dodecyl sulfate-polyacrylamide gels and renatured. PTP-5 had a neutral pH optimum, and using phosphotyrosyl-casein as substrate it had a Km of 130 nM and a Vmax of 10 mumol Pi released.min-1.mg protein-1. These kinetic parameters are well within the range of values obtained for other pure protein phosphatases. PTP-5 also dephosphorylated pp60v-src (autophosphorylated at Tyr-416) at 10% of the rate observed with phosphotyrosyl-casein. Additionally the ratio of phosphotyrosyl-casein/pp60v-src phosphatase activity was relatively constant throughout the PTP-5 purification procedure. These results indicate that PTP-5 is able to bind and efficiently dephosphorylate phosphotyrosyl-proteins and suggest that it is a physiologically relevant Tyr-protein phosphatase.
...
PMID:Phosphotyrosyl-protein phosphatases. I. Separation of multiple forms from bovine brain and purification of the major form to near homogeneity. 246 73

Two Tyr-protein phosphatase inhibitors, termed inhibitor H (Mr greater than 500,000) and inhibitor L (Mr 38,000), have been detected in bovine brain extracts. The inhibitors were partially purified by chromatography on DEAE-cellulose and Sephacryl S-300. Both inhibitors are proteins, as judged by their inactivation by proteinase K, and they exhibited remarkable stability during incubation at 95 degrees C. Of seven Tyr-protein phosphatase activities that we have isolated from bovine brain, PTP-4 and PTP-5 were most sensitive to the inhibitor proteins. Inhibition of the other five Tyr-protein phosphatases was only observed at very high inhibitor concentrations. The IC50 values for the inhibition of PTP-4 by inhibitor H and inhibitor L were 2- and 10-fold higher than those for the inhibition of PTP-5. Inhibition of PTP-5 by either inhibitor was rapid (maximum effect in less than 1 min) and readily reversed upon removal of the inhibitors by dilution. Inhibitor H and inhibitor L are distinct from the three heat-stable protein inhibitors of Ser/Thr-protein phosphatase 1. The ability of inhibitor H and inhibitor L to preferentially inhibit PTP-4 and PTP-5 provides an important new criterion that can be used to distinguish these enzymes from other Tyr-protein phosphatases. The two inhibitor proteins may be involved in regulating the activity of PTP-4 and PTP-5.
...
PMID:Phosphotyrosyl-protein phosphatases. II. Identification and characterization of two heat-stable protein inhibitors. 246 74

Rod cell outer segments were found to contain a protein phosphatase activity toward phosphoopsin with properties very similar to those of protein phosphatase 1 or 2A. The opsin phosphatase activity was stable to ethanol precipitation, had a Mr of 35,000-38,000 as determined by gel filtration, and was not dependent on divalent cations for activity. The chromatographic properties on DEAE-cellulose of the rod outer segment protein phosphatase were also similar to those reported for protein phosphatase 1 or 2A. In order to distinguish between these two protein phosphatases, we tested homogeneous preparations of protein phosphatases 1 and 2A from skeletal muscle for activity toward phosphoopsin. Protein phosphatase 2A dephosphorylated phosphoopsin at approximately 10% of its rate toward phosphorylase a, whereas protein phosphatase 1 had no activity toward phosphoopsin. We conclude that protein phosphatase 2A is present in the rod cell outer segment and that it is a likely candidate to perform the in vivo dephosphorylation of rhodopsin in the visual cycle.
...
PMID:The catalytic subunit of phosphatase 2A dephosphorylates phosphoopsin. 254 Jul 96

The enzyme amidotransferase [2-amino-2-deoxy-D-glucose-6-phosphate ketol isomerase (amino-transferring); EC 2.6.1.16] catalyzes the first step in the hexosamine biosynthetic pathway. In Blastocladiella emersonii the sensitivity of the enzyme to the inhibitor uridine-5'-diphospho-N-acetylglucosamine (UDP-GlcNAc) is developmentally regulated. The inhibitable form of amidotransferase activity present in the zoospore is converted to a noninhibitable form during germination. The latter form is present throughout the growth phase and sensitivity to UDP-GlcNAc gradually returns to the zoospore level during sporulation [C.P. Selitrennikoff, N.E. Dalley, and D.R. Sonneborn (1980) Proc. Natl. Acad. Sci. USA 77, 5998-6002]. The following evidence suggests that a phosphorylation/dephosphorylation mechanism underlies this interconversion: (i) Both the vegetative and zoospore enzymes have the same molecular weight of 140,000, but the vegetative enzyme elutes significantly earlier on a DEAE-cellulose column than does the zoospore enzyme. (ii) The increased sensitivity to UDP-GlcNAc occurring in vivo and in vitro correlates with increased phosphorylation of a polypeptide of apparent Mr 76,000. This component copurifies with amidotransferase activity through ion-exchange chromatography and sucrose density gradient centrifugation. (iii) Desensitization and concurrent dephosphorylation of sensitive amidotransferase can be observed in vitro after treatment with a partially purified magnesium-dependent phosphoprotein phosphatase from zoospores.
...
PMID:Phosphorylation-dependent regulation of amidotransferase during the development of Blastocladiella emersonii. 254 95

Neuromodulin (p57, GAP-43, F1, B-50) is a major neural-specific, calmodulin binding protein found in brain, spinal cord, and retina that is associated with membranes. Phosphorylation of neuromodulin by protein kinase C causes a significant reduction in its affinity for calmodulin (Alexander, K. A., Cimler, B. M., Meirer, K. E., and Storm, D. R. (1987) J. Biol. Chem. 262, 6108-6113). It has been proposed that neuromodulin may function to bind and concentrate calmodulin at specific sites within neurons and that activation of protein kinase C causes the release of free calmodulin at high concentrations near its target proteins. It was the goal of this study to determine whether bovine brain contains a phosphoprotein phosphatase that will utilize phosphoneuromodulin as a substrate. Phosphatase activity for phosphoneuromodulin was partially purified from a bovine brain extract using DEAE-Sephacel and Sephacryl S-200 gel filtration chromatography. The neuromodulin phosphatase activity was resolved into two peaks by Affi-Gel Blue chromatography. One of these phosphatases, which represented approximately 60% of the total neuromodulin phosphatase activity, was tentatively identified as calcineurin by its requirement for Ca2+ and calmodulin (CaM) and inhibition of its activity by chlorpromazine. Therefore, bovine brain calcineurin was purified to homogeneity and examined for its phosphatase activity against bovine phosphoneuromodulin. Calcineurin rapidly dephosphorylated phosphoneuromodulin in the presence of micromolar Ca2+ and 3 microM CaM. The apparent Km and Vmax for the dephosphorylation of neuromodulin, measured in the presence of micromolar Ca2+ and 2 microM CaM, were 2.5 microM and 70 nmol Pi/mg/min, respectively, compared to a Km and Vmax of 4 microM and 55 nmol Pi/mg/min, respectively, for myosin light chain under the same conditions. Dephosphorylation of neuromodulin by calcineurin was stimulated 50-fold by calmodulin in the presence of micromolar free Ca2+. Half-maximal stimulation was observed at a calmodulin concentration of 0.5 microM. We propose that phosphoneuromodulin may be a physiologically important substrate for calcineurin and that calcineurin and protein kinase C may regulate the levels of free calmodulin available in neurons.
...
PMID:Dephosphorylation of neuromodulin by calcineurin. 254 35


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---