Abstract
Control of the G1/S transition is a crucial regulatory point of commitment to cell division in plants. Plant cell cycle regulators, acting at the G1/S transition, share a high degree of similarity to their animal counterparts. D-type cyclin (CycD) is involved in the integration of environmental stimuli in response to external signals through the formation with the regulatory subunit of cyclin-dependent kinase (CDK) complexes.
We have investigated the regulation of cyclin/CDKA activity when stationary phase of tobacco BY-2 cells were diluted into fresh medium. p13Suc1-associated proteins contain cyclin/CDKA complexes and exhibit kinase activity against histone H1. Although kinase activity of p13Suc1-associated proteins rapidly increased at 6 h with the highest levels reached at 10 h, the level of CDKA protein bound to p13Suc1-beads were not changed during a 10-h period. This suggests that kinase activity of cyclin/CDKA complexes is regulated at the protein level.
