3.3 Spatiotemporal regulatory mechanism for the nuclear transportation of Nap1
Our computational results indicated that a spatiotemporal regulatory mechanism was involved in the nuclear transportation of Nap1, as supported by evidence from several previous studies. For example, it was reported that CK2 phosphorylates Ser 159 and Ser 177 and contributes to the regulatory mechanism depending on the cell cycle.7In the mutagenesis study of that report, the prevention of Nap1 phosphorylation resulted in a shortened G1 phase and a prolonged S phase.8 Taking these results together, it can be surmised that the phosphorylation of Nap1 might increase its turnover rate between the nucleus and cytosol to respond to nucleosome formation in the S phase. However, any thorough determination of the spatiotemporal regulation of Nap1 is difficult at the present time because there are currently no experimental data to support when/where Nap1 is phosphorylated in yeast. With further research progress in this area, it is expected that measurements of phosphorylation at a high spatiotemporal resolution will provide valuable evidence to reveal the function of Nap1.