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.