A novel M phase-specific H1 kinase recognized by the mitosis-specific monoclonal antibody MPM-2.
At the onset of mitosis, eukaryotic cells display an abrupt increase in a Ca2(+)- and cyclic nucleotide-independent histone H1 kinase activity, referred to as growth-associated or M phase-specific H1 kinase. The molecular basis for this activity is generally attributed to a kinase complex that consists of the p34cdc2 protein and cyclin, and exhibits maturation-promoting factor (MPF) activity. In the present study, we show that more than one kinase contributes to M phase-specific H1 kinase activity. When mature Xenopus oocyte extract prepared with ATP gamma S and NaF was fractionated by gel filtration, two prominent peaks of H1 kinase activity were detected, with apparent molecular masses of 600 and 150 kDa. The 150-kDa kinase copurified with the p34cdc2 protein and was immobilized by the suc 1 gene product p13 and anti-cyclin B2, which are specific for the cdc2 kinase complex. However, the 600-kDa kinase did not satisfy any of these criteria, thus identifying it as a novel M phase-specific H1 kinase. Only the 600-kDa kinase was recognized by the mitosis-specific monoclonal antibody, MPM-2, which inhibits Xenopus oocyte maturation and immunodepletes MPF activity. Furthermore, not only did the full activation of this kinase (MPM-2 kinase) coincide with the activation of MPF during the cell cycle, but also MPM-2 kinase-positive fractions obtained by gel filtration accelerated progesterone-induced oocyte maturation. It is, therefore, likely that MPM-2 kinase is a positive regulator in the M phase induction pathway.
Kuang
J
J
Department of Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston 77030.
Penkala
J E
JE
Wright
D A
DA
Saunders
G F
GF
Rao
P N
PN
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D016203:CDC2 Protein Kinase / Q000276:immunology; D016200:Maturation-Promoting Factor / Q000145:classification / Q000276:immunology* / Q000378:metabolism; D008938:Mitosis; D008970:Molecular Weight; D009865:Oocytes / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology; D014982:Xenopus laevis
D000911:Antibodies, Monoclonal; D011374:Progesterone; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor