1985 Fiscal Year Final Research Report Summary
<Ca^(2+)> regulatory mechanism of smooth muscle contraction
| Project/Area Number |
59440025
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurophysiology and muscle physiology
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| Research Institution | Okazaki National Research Institutes |
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Principal Investigator |
EBASHI Setsuro 岡崎国立共同研究機構, その他, 教授 (10009863)
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| Project Period (FY) |
1984 – 1985
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| Keywords | 平滑筋収縮の【Ca^(2+)】調節 / ライオトニン / ミオシン軽鎖リン酸化 |
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| Research Abstract |
Phosphorylation of myosin light chains by Ca-calmodulin dependent kinase is now widely believed to be the molecular mechanism of Ca-regulated activation of smooth muscle contraction. We have, however, proposed that the actin-binding protein, named 'leiotonin', is the real activator. In the present study, following results have been obtained, all of which demonstrate the discrepancy between 'kinase activity' and contraction-. stimulating activity.
1) Digestion of 'activator fraction' by <V_8> protease, CANP or trypsin scarcely affected its kinase activity, but almost completely destroyed its contraction-stimulating activity.
2) Chemical modification of Lys, Tyr or Cys residues of 'activator fraction' resulted in the loss of its contraction-stimulating activity, while sparing its kinase activity.
3) Kinase activity was decreased with increase in pH from 6.8 to 8.0, while contraction-stimulating activity was almost the same in that range of pH.
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