| タイトル | Plant chimeric Ca2+/Calmodulin-dependent protein kinase. Role of the neural visinin-like domain in regulating autophosphorylation and calmodulin affinity |
| 著者（英） | Cremo, C. R.; Sathyanarayanan, P. V.; Poovaiah, B. W. |
| 発行日 | 2000-09-29 |
| 言語 | eng |
| 内容記述 | Chimeric Ca(2+)/calmodulin-dependent protein kinase (CCaMK) is characterized by a serine-threonine kinase domain, an autoinhibitory domain, a calmodulin-binding domain and a neural visinin-like domain with three EF-hands. The neural visinin-like Ca(2+)-binding domain at the C-terminal end of the CaM-binding domain makes CCaMK unique among all the known calmodulin-dependent kinases. Biological functions of the plant visinin-like proteins or visinin-like domains in plant proteins are not well known. Using EF-hand deletions in the visinin-like domain, we found that the visinin-like domain regulated Ca(2+)-stimulated autophosphorylation of CCaMK. To investigate the effects of Ca(2+)-stimulated autophosphorylation on the interaction with calmodulin, the equilibrium binding constants of CCaMK were measured by fluorescence emission anisotropy using dansylated calmodulin. Binding was 8-fold tighter after Ca(2+)-stimulated autophosphorylation. This shift in affinity did not occur in CCaMK deletion mutants lacking Ca(2+)-stimulated autophosphorylation. A variable calmodulin affinity regulated by Ca(2+)-stimulated autophosphorylation mediated through the visinin-like domain is a new regulatory mechanism for CCaMK activation and calmodulin-dependent protein kinases. Our experiments demonstrate the existence of two functional molecular switches in a protein kinase regulating the kinase activity, namely a visinin-like domain acting as a Ca(2+)-triggered switch and a CaM-binding domain acting as an autophosphorylation-triggered molecular switch. |
| NASA分類 | Life Sciences (General) |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/298557 |
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