p34cdc2

p34cdc2 is a protein kinase which is activated when cells are committed to division. In eukaryotic cells, a cell undergoes G1 (gap or growth stage 1), S (DNA replication), G2 (gap or growth stage 2), and M (mitosis) phases leading to cell division. In typical mammalian cells, there are two checkpoints in the cell division cycle, the G1/S and G2/M transitions, respectively. When the cell is passing G1/S transition, it is considered "committed". Although p34 is shown widely to be present all the time, its activity oscillates through phosphorylation (getting a phosphate group at certain serine/tyrosine residues in the protein) and dephosphorylation (removing a phosphate group from some of the phosphorylated sites). The activated p34cdc2 bind with cyclin B and form a mitosis promoting factor (MPF) which trigers events of mitosis and cell division.

p34cdc2 is highly conserved across wide range of taxa. Its presence has been suspected earlier for freshwater alga like Chlamydomonas, this protein and its encoded gene was first detected and characterized for marine phytoplankton in our laboratory (Lin and Carpenter 1999).