Molecular characterization of the murine thymidylate kinase gene.
Thymidylate kinase (TMK) catalyzes an essential reaction of converting dTMP to dTDP, leading to formation of the DNA precursor dTTP. Unlike the preceding enzymes, thymidine kinase and thymdylate synthase, little is known about regulation of TMK after mammalian cells exit from quiescence and enter the cell cycle. In this study, cDNA of murine TMK was isolated and characterized. Murine TMK gene expression in nontransformed BALB/c 3T3 cells was shown to be regulated during Gø to S-phase transit at both mRNA and enzyme activity levels. Its timing was distinctive from that of thymidine kinase and thymdylate synthase. In contrast, the regulation of TMK in response to serum growth factor stimulation was abolished in cells transformed by either SV40 or Kirsten viruses, and tmk expression became constitutively elevated. This finding is in concordance with previous results showing that transformed cells exhibit more relaxed control than normal cells in their initiation of DNA replication.
Liang
P
P
Division of Cell Growth and Regulation, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.
Averboukh
L
L
Zhu
W
W
Haley
T
T
Pardee
A B
AB
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D002461:Cell Line, Transformed; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D005796:Genes / Q000235:genetics; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007708:Kirsten murine sarcoma virus; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009703:Nucleoside-Phosphate Kinase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA; D013539:Simian virus 40; D013937:Thymidine Kinase / Q000235:genetics; D013940:Thymidylate Synthase / Q000235:genetics
D018076:DNA, Complementary; D006133:Growth Substances; D012333:RNA, Messenger; D013940:Thymidylate Synthase; D013937:Thymidine Kinase; D009703:Nucleoside-Phosphate Kinase; C020093:dTMP kinase