The cdc2Ms kinase is differently regulated in the cytoplasm and in the nucleus

• Published in: Plant physiology (Bethesda) Vol. 113; no. 3; pp. 841 - 852
• Main Authors: BÖGRE, L, ZWERGER, K, MESKIENE, I, BINAROVA, P, CSIZMADIA, V, PLANCK, C, WAGNER, E, HIRT, H, HEBERLE-BORS, E
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.03.1997
• Subjects: actividad enzimatica; activite enzymatique; Alfalfa; anatomia de la planta; anatomie vegetale; anion; aniones; anions; Antibodies; binding proteins; Biological and medical sciences; Cell Biology and Signal Transduction; Cell cycle; cell division; Cell kinetics; Cell physiology; citoplasma; culture media; cytoplasm; cytoplasme; developmental stages; division cellulaire; division celular; enzyme inhibitors; enzymic activity; etapas de desarrollo; fosfatos; Fundamental and applied biological sciences. Psychology; Histones; Immunoprecipitation; inhibidores de enzimas; inhibiteur d' enzyme; Interphase; measurement; medicago sativa; medicion; medio de cultivo; mesure; milieu de culture; Mitosis; noyau cellulaire; nucleo; nucleus; phosphate; phosphates; plant anatomy; Plant cells; Plant physiology and development; proteinas aglutinantes; proteine de liaison; Proteins; purificacion; purification; stade de developpement; transferasas; transferase; transferases; Yeasts; Purification; Enzyme; Transferases; Cell nucleus; Medicago sativa; Cyclin; Metabolic inhibitor; Immunological method; Characterization; Leguminosae; Enzymatic activity; Protein kinase; Dicotyledones; Angiospermae; Cell cycle; Spermatophyta; Inhibition; Localization; Cytoplasm
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.113.3.841

To study a cyclin-dependent kinase (CDK) from alfalfa (Medicago sativa L.), an antibody was raised against the C-terminal 16 amino acids of the protein cdc2aMs. The cdc2Ms protein was immunopurified with this antibody and its histone kinase activity was measured. The cdc2Ms kinase is activated at the Gus transition when phosphate-starved cells from the G0 phase re-enter the cell cycle and remain active as cells transit the S, G2, and M phases, indicating that the same CDK regulates all of these phases in alfalfa. In contrast, when cdc2Ms kinase was purified by binding to p13suc1, it was active only in the G2 and M phases. In immunoblots the C-terminal antibody detected an equal amount of the cdc2Ms protein in the cytoplasm and in the nucleus. By indirect immunofluorescence, however, the cytoplasmic form of cdc2Ms could not be found in the S phase of the cells, indicating that the epitope for the cdc2 antibody is not accessible. Binding of putative inhibitor proteins to cdc2 was shown by inactivation of purified plant CDK when cell extracts were added. Furthermore, purified CDK inhibitors, such as the mouse p27kip1 and the yeast p40sic1, blocked the purified plant CDK activity.