Changes in the level of the Cdc2Os3 protein in
response to cell-cycle blockers. a, Specific cross-reactions of the
GST-Cdc2Os2 and GST-Cdc2Os3 fusion proteins with antibodies. One
microgram of each GST-fusion protein was subjected to immunoblotting
with antibodies against Cdc2Os2 or Cdc2Os3. Lanes 1, GST-Cdc2Os1; lanes
2, GST-Cdc2Os2; and lanes 3, GST-Cdc2Os3. b, Immunological detection of
Cdc2Os2 (p40) and Cdc2Os3 (p36) in suspension-cultured rice cells that
had been treated with cell-cycle blockers. Total protein was extracted
from cultured cells after no treatment (NT) and after treatment with
colchicine (CO) or hydroxyurea (HU). Twenty micrograms of each sample
was subjected to immunoblotting with Cdc2Os2- or Cdc2Os3-specific
antibodies. c, Histone H1-kinase activities in the immunoprecipitates
obtained with the antibodies. Total protein was extracted from cultured
cells as described above and used for immunoprecipitation with Cdc2Os2-
or Cdc2Os3-specific antibodies. Immunoprecipitates were subjected to
the histone H1-kinase assay, and phosphorylated histone H1 was
detected.