Activation of M-phase-specific histone H1 kinase by modification of the phosphorylation of its p34cdc2 and cyclin components.
An M-phase-specific histone H1 kinase (H1K) has been described in a wide variety of eukaryotic cell types undergoing the G2/M transition in the cell division cycle. We have used p13suc1-Sepharose affinity chromatography to purify H1K to near homogeneity from matured starfish oocytes. A yield of 67% was obtained. Active H1K behaves as a 90- to 100-kD protein and appears to be constituted of equimolar amounts of cyclin and p34cdc2. The p34cdc2 subunit becomes tyrosine-dephosphorylated as the H1K is activated during entry of the oocytes into M phase, whereas the cyclin subunit is reciprocally phosphorylated. Acid phosphatase treatment of inactive p34cdc2/cyclin complex induces p34cdc2 dephosphorylation and three- to eightfold stimulation of the enzyme activity. These results suggest that active M-phase-specific H1K is constituted of both dephosphorylated p34cdc2 and phosphorylated cyclin.
Pondaven
P
P
Centre National de la Recherche Scientifique, Station Biologique, France.
Meijer
L
L
Beach
D
D
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D016203:CDC2 Protein Kinase; D002846:Chromatography, Affinity; D016213:Cyclins; D004789:Enzyme Activation; D007447:Invertebrate Hormones / Q000378:metabolism*; D008938:Mitosis; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D006656:Protamine Kinase / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D013215:Starfish
D016213:Cyclins; D007447:Invertebrate Hormones; D010750:Phosphoproteins; D011494:Protein Kinases; D006656:Protamine Kinase; D016203:CDC2 Protein Kinase; D000135:Acid Phosphatase