Aniko Rokolya

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Myosin light chain phosphorylation in aortic smooth muscle homogenate reached a maximal level of 0.75 mol phosphate/mol light chain, and then declined. Addition of okadaic acid led to a sustained phosphorylation level of 1.7 mol/mol. In the absence of okadaic acid, phosphorylation was predominantly due to myosin light chain kinase, whereas in the presence(More)
We have tested the hypothesis of Winder and Walsh [(1990) J. Biol. Chem. 265, 10148] that the contractile state of smooth muscle is regulated by calponin phosphorylation. Porcine carotid arterial muscles were highly labeled with 32P, then contracted with four different agents for various times. No radioactivity was detected in calponin isolated by 2D or 1D(More)
Calponin inhibits actin-activated myosin adenosinetriphosphatase (ATPase) activity, and phosphorylation reverses this inhibition. Calponin phosphorylation has been demonstrated in reconstituted contractile protein systems, but studies using intact smooth muscle have produced mixed results. The goal of this study was to determine if vascular smooth muscle(More)
Ca(+)/calmodulin-dependent protein kinase II (CaM kinase II) has been implicated in the regulation of smooth muscle contractility. The goals of this study were to determine: 1) to what extent CaM kinase II is activated by contractile stimuli in intact arterial smooth muscle, and 2) the effect of a CaM kinase II inhibitor (KN-93) on CaM kinase II activation,(More)
Stretching of porcine carotid arterial muscle increased the phosphorylation of the 20 kDa myosin light chain from 0.23 to 0.68 mol [32P]phosphate/mol light chain, whereas stretching of phorbol dibutyrate treated muscle increased the phosphorylation from 0.30 to 0.91 mol/mol. Two-dimensional gel electrophoresis followed by two-dimensional tryptic(More)
Agonist activation enhances smooth muscle myofilament Ca2+ sensitivity. The increased force accompanying receptor stimulation (over Ca2+ alone) requires GTP and is reversed by GDP beta S, demonstrating a G-protein dependence. Protein kinase C (PKC) activators, such as phorbol esters, mimic and PKC inhibitors block the agonist-induced increase in Ca2+(More)
Two types of myosin light chain phosphatase from aortic smooth muscle extract were separated by chromatography on heparin-agarose. The phosphatase which appeared in the flow-through fractions had low activity on actomyosin, its apparent molecular mass was 260 kDa and upon ethanol treatment it generated a catalytic subunit with an apparent molecular mass of(More)
Calponin, a thin filament-associated protein, inhibits actin-activated myosin ATPase activity, and this inhibition is reversed by phosphorylation. Calponin phosphorylation by protein kinase C and Ca2+/calmodulin-dependent protein kinase II has been shown in purified protein systems but has been difficult to demonstrate in more physiological preparations. We(More)
Phosphorylation of myosin light chain (LC) isoforms in arterial actomyosin can be induced by endogenous kinases upon addition of Mg2+ and ATP. The extent of phosphorylation in the presence of 2 mM ethylene glycol bis(beta-aminoethyl ether)N,N'-tetraacetic acid (EGTA), 0.2 mM Ca2+, or 0.2 mM Ca2+ plus calmodulin is 1.6, 2.1, and 2.3 mol phosphate/mol LC,(More)
Telokin is identical in sequence to the C-terminal portion of myosin light chain kinase but is expressed independently. We have used monoclonal antibodies specific to the non-telokin portion of myosin light chain kinase and to telokin, immunofluorescence microscopy and image reconstruction to demonstrate the presence of telokin in cardiac myocytes and to(More)