Biomaterial Database

Identification and changes in activity of five thymidine kinase forms during the cell cycle of Physarum polycephalum. 1983

M Pahlic, and J J Tyson

Five forms of thymidine kinase have been identified on isoelectric focusing gels of Physarum polycephalum supernatants. Their isoelectric points are 5.9, 6.4, 6.7, 6.9 and 7.1. All are inhibited by deoxythymidine 5'-triphosphate (dTTP). The activity of the pI 7.1 form does not change significantly during the cell cycle. The other four forms change in activity. About 1 h before metaphase the activity of the four more acidic forms is first detected. Their activity peaks during telophase, and by 1 h after metaphase there is a 50% decrease in activity of the 5.9 form. By 3 h after metaphase the activity of the 6.4 form has dropped more sharply than the activity of the 6.7 form. By 6 h after metaphase only the activity of the 6.9 form is present in significant amounts in addition to the 7.1 form. The activity of these new acidic forms probably accounts for the reported increase in total thymidine kinase activity during mitosis and early S phase.

UI	MeSH Term	Description	Entries
D007399	Interphase	The interval between two successive CELL DIVISIONS during which the CHROMOSOMES are not individually distinguishable. It is composed of the G phases (G1 PHASE; G0 PHASE; G2 PHASE) and S PHASE (when DNA replication occurs).	Interphases
D007526	Isoelectric Point	The pH in solutions of proteins and related compounds at which the dipolar ions are at a maximum.	Isoelectric Points,Point, Isoelectric,Points, Isoelectric
D008677	Metaphase	The phase of cell nucleus division following PROMETAPHASE, in which the CHROMOSOMES line up across the equatorial plane of the SPINDLE APPARATUS prior to separation.
D010804	Physarum	A genus of protozoa, formerly also considered a fungus. Characteristics include the presence of violet to brown spores.	Physarums
D002453	Cell Cycle	The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.	Cell Division Cycle,Cell Cycles,Cell Division Cycles,Cycle, Cell,Cycle, Cell Division,Cycles, Cell,Cycles, Cell Division,Division Cycle, Cell,Division Cycles, Cell
D013692	Telophase	The final phase of cell nucleus division following ANAPHASE, in which two daughter nuclei are formed, the CYTOPLASM completes division, and the CHROMOSOMES lose their distinctness and are transformed into CHROMATIN threads.	Telophases
D013937	Thymidine Kinase	An enzyme that catalyzes the conversion of ATP and thymidine to ADP and thymidine 5'-phosphate. Deoxyuridine can also act as an acceptor and dGTP as a donor. (From Enzyme Nomenclature, 1992) EC 2.7.1.21.	Deoxythymidine Kinase,Deoxypyrimidine Kinase,Kinase, Deoxypyrimidine,Kinase, Deoxythymidine,Kinase, Thymidine
D013938	Thymidine Monophosphate	5-Thymidylic acid. A thymine nucleotide containing one phosphate group esterified to the deoxyribose moiety.	DTMP,TMP,Thymidylic Acid,Deoxythymidylate,Thymidylic Acids,Acid, Thymidylic,Acids, Thymidylic,Monophosphate, Thymidine