An aortic spontaneously active phosphatase dephosphorylates myosin and inhibits actin-myosin interaction |
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Authors: | Joseph Di Salvo Donetta Gifford Corinna Bialojan JCaspar Rüegg |
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Institution: | Department of Physiology, University of Cincinnati, College of Medicine, 231 Bethesda Avenue, M.L. #576, Cincinnati, OH 45267 USA;II Physiologisches Institut, Universität Heidelberg, D-69 Heidelberg, Federal Republic of Germany |
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Abstract: | Actin-myosin interaction in aortic actomyosin reportedly requires phosphorylation of the 20,000 dalton myosin light chains. A spontaneously active phosphatase which dephosphorylates phosphorylase and isolated phosphorylated cardiac myosin light chains was extracted from bovine aortic smooth muscle. This enzyme, when added to aortic native actomyosin (a) significantly suppressed phosphorylation of the light chains of the native hexameric smooth muscle myosin, (b) accelerated the rate and increased the magnitude of myosin light chain dephosphorylation in actomyosin that had been prephosphorylated, and (c) markedly attenuated the rate of actin-myosin interaction. These results support the hypothesis that myosin phosphorylation and subsequent actin-myosin interactions (contractility) in vascular smooth muscle may be modulated by spontaneously active aortic phosphatase. |
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Keywords: | To whom all correspondence should be addressed |
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