These authors contributed equally to this work.
Casein kinase activity in etiolated Cucumis sativus cotyledons
Article first published online: 29 APR 2009
© 2009 German Botanical Society and The Royal Botanical Society of the Netherlands
Volume 12, Issue 1, pages 134–144, January 2010
How to Cite
Vidal, D., Alvarez-Flórez, F. and Simón, E. (2010), Casein kinase activity in etiolated Cucumis sativus cotyledons. Plant Biology, 12: 134–144. doi: 10.1111/j.1438-8677.2009.00212.x
- Issue published online: 8 DEC 2009
- Article first published online: 29 APR 2009
- Received: 3 November 2008; Accepted: 12 March 2009
- Casein kinase activity;
- casein kinase inhibitors;
- circadian rhythm;
- cucumber (Cucumis sativus L.);
- protein phosphorylation
Two calcium- and light-dependent protein kinases have been reported in etiolated Cucumis sativus cotyledons (Vidal et al. 2007). In the present work, we studied casein kinase (CK) activity in etiolated cucumber cotyledons of in-gel and in vitro kinase assays, using specific CK inhibitors, and ATP and GTP as phosphate donors. Two proteins with CK activity were detected in both casein gels and autophosphorylation assays. One of them, with a molecular mass of approximately 36 kDa, showed biochemical CK1 characteristics: it was inhibited by specific CK1 inhibitors and only used ATP as phosphate donor. The second, with a molecular mass of approximately 38 kDa, had CK2 characteristics; it used both ATP and GTP as phosphate donors, was inhibited by all specific CK2 inhibitors, and was recognized by a polyclonal antibody directed against the α catalytic subunit of a CK2 from tobacco. The kinase activity of the CK2 detected in etiolated cucumber cotyledons showed circadian rhythmicity in both in vitro and in-gel casein phosphorylation and in autophosphorylation assays. Thus, our results suggest that the CK2 of approximately 38 kDa could be related to the circadian oscillator of C. sativus cotyledons.