Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calponin, a thin-filament protein of smooth muscle, has been implicated in the regulation of smooth-muscle contraction, since in vitro the isolated protein inhibits the actin-activated myosin MgATPase. This inhibitory effect, and the ability of calponin to bind to actin, is lost after its phosphorylation by protein kinase C or Ca2+/calmodulin-dependent protein kinase II [Winder & Walsh (1990) J. Biol. Chem. 265, 10148-10155]. If this phosphorylation reaction is of physiological significance, there must be a protein phosphatase in smooth muscle capable of dephosphorylating calponin and restoring its inhibitory effect on the actomyosin MgATPase. We demonstrate here the presence, in chicken gizzard smooth muscle, of a single major phosphatase activity directed towards calponin. This phosphatase was purified from the soluble fraction of chicken gizzard by (NH4)2SO4 fractionation and sequential chromatography on Sephacryl S-300, DEAE-Sephacel, omega-amino-octyl-agarose and thiophosphorylated myosin 20 kDa light-chain-Sepharose columns. The purified phosphatase contained three polypeptide chains of 60, 55 and 38 kDa which were shown to be identical with the subunits of SMP-I, a smooth-muscle phosphatase capable of dephosphorylating the isolated 20 kDa light chain of myosin but not intact myosin [Pato & Adelstein (1983) J. Biol. Chem. 258, 7047-7054]. Consistent with its identity with SMP-I, calponin phosphatase was classified as a type-2A protein phosphatase. Of several potential phosphoprotein substrates examined, calponin proved to be kinetically the best, suggesting that calponin may be a physiological substrate for this phosphatase. Finally, dephosphorylation of calponin which had been phosphorylated by protein kinase C restored completely its ability to inhibit the actin-activated MgATPase of smooth-muscle myosin. These observations support the hypothesis that calponin plays a role in regulating the contractile state of smooth muscle and that this function in turn is controlled by phosphorylation-dephosphorylation.
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PMID:Purification and characterization of calponin phosphatase from smooth muscle. Effect of dephosphorylation on calponin function. 132 79

Caldesmon phosphatase was identified in chicken gizzard smooth muscle by using as substrates caldesmon phosphorylated at different sites by protein kinase C, Ca2+/calmodulin-dependent protein kinase II and cdc2 kinase. Most (approximately 90%) of the phosphatase activity was recovered in the cytosolic fraction. Gel filtration after (NH4)2SO4 fractionation of the cytosolic fraction revealed a single major peak of phosphatase activity which coeluted with calponin phosphatase [Winder, Pato and Walsh (1992) Biochem. J. 286, 197-203] and myosin LC20 phosphatase. Further purification of caldesmon phosphatase was achieved by sequential chromatography on columns of DEAE-Sephacel, omega-amino-octyl-agarose, aminopropyl-agarose and thiophosphorylated myosin LC20-Sepharose. A single peak of caldesmon phosphatase activity was detected at each step of the purification. The purified phosphatase was identified as SMP-I [Pato and Adelstein (1980) J. Biol. Chem. 255, 6535-6538] by subunit composition (three subunits, of 60, 55 and 38 kDa) and Western blotting using antibodies against the holoenzyme which recognize all three subunits and antibodies specific for the 38 kDa catalytic subunit. SMP-I is a type 2A protein phosphatase [Pato, Adelstein, Crouch, Safer, Ingebritsen and Cohen (1983) Eur. J. Biochem. 132, 283-287; Winder et al. (1992), cited above]. Consistent with the conclusion that SMP-I is the major caldesmon phosphatase of smooth muscle, purified SMP-I from turkey gizzard dephosphorylated all three phosphorylated forms of caldesmon, whereas SMP-II, -III and -IV were relatively ineffective. Kinetic analysis of dephosphorylation by chicken gizzard SMP-I of the three phosphorylated caldesmon species and calponin phosphorylated by protein kinase C indicates that calponin is a significantly better substrate of SMP-I than are any of the three phosphorylated forms of caldesmon. We therefore suggest that caldesmon phosphorylation in vivo can be maintained after kinase inactivation due to slow dephosphorylation by SMP-I, whereas calponin and myosin are rapidly dephosphorylated by SMP-I and SMP-III/SMP-IV respectively. This may have important functional consequences in terms of the contractile properties of smooth muscle.
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PMID:Smooth-muscle caldesmon phosphatase is SMP-I, a type 2A protein phosphatase. 839 39

Here we show that brain-derived neurotrophic factor (BDNF) stimulates both the phosphorylation of the Ca2+/calmodulin-dependent protein kinase 2 (CaMK2) and its kinase activity in rat hippocampal slices. In addition, we find that: (i) the time course of BDNF action is not accompanied by a change in the spectrum of either alpha- and beta-subunits of CaMK2 detected by immunoblotting; (ii) both treatment of solubilized CaMK2 with alkaline phosphatase and treatment of immunoprecipitated CaMK2 with protein phosphatase 1 reverse phosphorylation and activation of the kinase; (iii) phospholipase C inhibitor D609 and intracellular Ca2+ chelation by 1,2-bis-(o-aminophenoxy)ethane-N,N,N",N',-tetracetic acid tetra(acetoxymethyl)ester or 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate but not omission of Ca2+ or Ca2+ chelation by EGTA, abolish the stimulatory effect of BDNF on phosphorylation and activation of CaMK2. These results strongly suggest that the conversion of CaMK2 into its active, autophosphorylated form, but not its concentration, is increased by BDNF via stimulation of phospholipase C and subsequent intracellular Ca2+ mobilization.
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PMID:Brain-derived neurotrophic factor increases Ca2+/calmodulin-dependent protein kinase 2 activity in hippocampus. 930 59

ATP/dithiothreitol (DTT)-stimulated guanylate cyclase (GC) in lung membrane was stimulated 18-fold by ATP and DTT, and both its activity and atrial natriuretic peptide (ANP)-stimulated GC activity were observed to be additive. ATP/DTT-stimulated GC was solubilized by octyl glucoside (OG) to examine the mechanism of ATP/DTT-stimulation. GC in OG-extracts was stimulated maximally 2.5-fold by both ATP, ATPgammaS or AMPPNP, and DTT. Preincubation of OG-extracts at 10 degrees C with AMPPNP and DTT (1st-preincubation) converted GC to an insensitive state to stimulation by both ATP and DTT, and this conversion was partly inhibited by a protein phosphatase-1 inhibitor (10-1,000 nM okadaic acid). On the other hand, ANP-stimulated GC was not converted to an insensitive state to ANP/ATP-stimulation by the 1st-preincubation. Subsequent preincubation of OG-extracts at 10 degrees C with both DTT and, ATP or ATPgammaS but not AMPPNP converted GC to a state sensitive to ATP/DTT-stimulation, and this conversion was partly inhibited by inhibitors of Ca2+/calmodulin-dependent protein kinase II (KN-62 and KN-93). In contrast, the preincubation with KN-62 and KN-93 had no effect on ANP-stimulated GC activity. The results suggested that phosphorylation was involved in the regulation of ATP/DTT-stimulated GC sensitivity to ATP/DTT-stimulation and that ATP/DTT-stimulated GC activity was likely to be a different type from ANP-stimulated GC activity.
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PMID:Regulation of guanylate cyclase by ATP and dithiothreitol in rat lung membrane: involvement of an insensitive and a sensitive state to ATP/dithiothreitol-stimulation. 1208 46

The release of a fertilizable oocyte from the ovary is dependent upon the expansion of the cumulus cells. The expansion requires cooperation between epidermal growth factor (EGF) family peptide-activated mitogen-activated protein kinase (MAPK)3/1 and oocyte paracrine factor-activated-Sma- and Mad-related protein (SMAD)2/3 signaling in cumulus cells. However, the mechanism underlying (MAPK)3/1 signaling is unclear. In the present study, the EGF-activation of EGF receptor (EGFR) induced cyclic adenosine 3',5'-monophosphate (cAMP) response element-binding protein (CREB) phosphorylation in cumulus cells, and the interruption of CREB functional complex formation by naphthol AS-E phosphate (KG-501) completely blocked the EGF-stimulated expansion-related gene expression. EGF-stimulated phosphorylation of CREB was completely inhibited by MAPK3/1 inhibitor U0126, suggesting that EGF-activated MAPK3/1 results in the activation of CREB for cumulus expansion. Also, the role of EGF-stimulated calcium signaling was studied. Calcium-elevating reagents ionomycin and sphingosine-1-phosphate mimicked, but calcium chelators bis-(o'aminophenoxy)-ethane-N,N,N,N-tetraacetic acid, tetra(acetoxymethyl)-ester, and 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate abolished the activity of EGF on CREB phosphorylation, cumulus expansion, and expansion-related gene expression. Furthermore, EGF-induced cumulus expansion was inhibited by calmodulin (CaM)-dependent protein kinase II (CaMKII) inhibitors, KN-93 and autocamtide-2-related inhibitory peptide. However, the inhibition of SMAD2/3 activity by removal of oocyte from cumulus-oocyte complexes did not affect the EGF-induced CREB phosphorylation, indicating that EGF-activated CREB is independent of oocyte-activated SMAD2/3 signaling. Therefore, EGF-induced CREB activity by MAPK3/1 and Ca2+ /CaMKII signaling pathways promotes the expansion-related gene expression and consequent cumulus expansion.
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PMID:CREB activity is required for epidermal growth factor-induced mouse cumulus expansion. 3163 99