Tea catechin, epigallocatechin‐3‐gallate suppresses myosin II regulatory light chain phosphorylation
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Abstract Phosphorylation of myosin II regulatory light chain (MRLC) is critical event for many cellular processes including muscle contraction, mytosis, migration, and exocytosis. Epigallocatechin‐3‐ O ‐gallate (EGCG) is a major polyphenolic compound of green tea and has various physiological functions. We found that EGCG disrupted stress fibers and suppressed the MRLC phosphorylation in HeLa cells. To elucidate the mechanism for the suppressive effect on the phosphorylation, we examined the effect of various inhibitors for kinases that modulate MRLC phosphorylation. None of the inhibitors mimic the activity of EGCG. These results suggest that EGCG is a compound that can suppress MRLC phosphorylation.Keywords:
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Epicatechin gallate
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Chemotactic stimulation of the cellular slime mould Dictyostelium discoideum by cyclic AMP increases the incorporation of 32 P into a 210‐kDa polypeptide. This was determined in lysates prepared from stimulated and nonstimulated cells. Earlier results suggesting that the 210‐kDa polypeptide corresponds to myosin heavy chains [7] have now been confirmed. We have investigated the sequence of events following chemotactic stimulation that lead to the change of myosin heavy‐chain phosphorylation. Chemotactic stimulation did not activate myosin heavy chain kinase, but seemed to elicit the transient accumulation of dephosphorylated myosin heavy chains. Thus, the inefficient incorporation of 32 P into myosin heavy chains in lysates of control cells seems to be due to the lack of dephosphorylated myosin heavy chains. Using membranes of aggregation‐competent cells. we found that incorporation of 32 P into myosin heavy chains was inhibited by 0. 1–1 mM Ca 2+ . The effect of calcium seems to be mediated by endogeneous calmodulin and was due to the inhibition of myosin kinase activity rather than to the activation of myosin phosphatase. By the addition of calmodulin, the inhibition of myosin heavy‐chain phosphorylation was further enhanced. Folic acid, an attractant of undifferentiated cells, also caused enhanced incorporation of 32 P into myosin heavy chains, as determined in cell lysates. The amount of 32 P incorporated in response to cyclic AMP into myosin heavy chains increased during differentiation to the aggregation‐competent stage. Only a small fraction of the cell surface receptors had to be activated in order to elicit a maximal reaction. Our results suggest that a phosphorylated form of myosin heavy chains prevails at the onset of the chemotactic response and that dephosphorylation begins within 5–10 s at 23°C.
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Dephosphorylation
Meromyosin
Myosin-light-chain phosphatase
Myofilament
Myofibril
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Drosophila ninaC gene encodes myosin homologous proteins which are classified as myosin III of the myosin superfamily, yet the physiological and biochemical function of myosin III has not characterized. We report here that myosin III does exhibit protein kinase activity. The kinase homologous domain (MYOIIIPK) of myosin III was expressed in the baculovirus expression system and purified to homogeneity. MYOIIIPK phosphorylated a number of proteins including myosin III p132 and smooth muscle myosin regulatory light chain (LC20), suggesting that myosin III is a multifunctional protein kinase. The phosphoamino acid analysis revealed that myosin III is a serine/threonine kinase but not a tyrosine kinase. The observation that MYOIIIPK phosphorylates myosin III suggests that the autophosphorylation might play a role for the regulation of myosin III function. This is the first direct demonstration of kinase activity for the myosin III class.
Meromyosin
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The DNA cleavage activities of (+)-catechin (C), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), and (-)-epigallocatechin gallate (EGCg) were examined with 16 different metal ions. Cu2+ with all the catechins facilitated DNA cleavage, while Ag+ with EGC and EC showed a strong repressive effect. The other metal ions examined showed little effect.
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Journal Article Conformation and Activity of Smooth Muscle Myosin Probed by Various Essential Light Chains Get access Tsuyoshi Katoh, Tsuyoshi Katoh Division of Chemistry, Graduate School of Science, Hokkaido UniversityKita-ku, Sapporo 060 Search for other works by this author on: Oxford Academic PubMed Google Scholar Fumi Morita Fumi Morita Division of Chemistry, Graduate School of Science, Hokkaido UniversityKita-ku, Sapporo 060 Search for other works by this author on: Oxford Academic PubMed Google Scholar The Journal of Biochemistry, Volume 121, Issue 1, January 1997, Pages 56–62, https://doi.org/10.1093/oxfordjournals.jbchem.a021570 Published: 01 January 1997 Article history Received: 12 August 1996 Published: 01 January 1997
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The myosin holoenzyme is a multimeric protein complex consisting of heavy chains and light chains. Myosin light chains are calmodulin family members which are crucially involved in the mechanoenzymatic function of the myosin holoenzyme. This review examines the diversity of light chains within the myosin superfamily, discusses interactions between the light chain and the myosin heavy chain as well as regulatory and structural functions of the light chain as a subunit of the myosin holoenzyme. It covers aspects of the myosin light chain in the localization of the myosin holoenzyme, protein-protein interactions and light chain binding to non-myosin binding partners. Finally, this review challenges the dogma that myosin regulatory and essential light chain exclusively associate with conventional myosin heavy chains while unconventional myosin heavy chains usually associate with calmodulin.
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Antioxidative activity of (-)-epigallocatechin-3-(3''-O-methyl)gallate (catechin e) was examined. Catechin e showed a strong antioxidative activity. A preliminary test using rat cancer cells suggests that catechin e also has a strong cytotoxic activity. Among tested catechins, only catechin e has strong activity for both.
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Gallate
Epicatechin gallate
Deep eutectic solvent
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Meromyosin
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