Catalyzes the reversible phosphorylation of deoxythymidine monophosphate (dTMP) to deoxythymidine diphosphate (dTDP), using ATP as its preferred phosphoryl donor. Situated at the junction of both de novo and salvage pathways of deoxythymidine triphosphate (dTTP) synthesis, is essential for DNA synthesis and cellular growth. Has a broad specificity for nucleoside triphosphates, being highly active with ATP or dATP as phosphate donors, and less active with ITP, GTP, CTP and UTP. ATP + dTMP = ADP + dTDP Binds 1 Mg(2+) ion per subunit. This ion is required for catalysis, binding to the active site transiently (at the TMP-binding site), and probably acting as a clamp between the phosphoryl donor and acceptor. Competitively inhibited at the phosphate acceptor site by 3'-azido-3'-deoxythymidine monophosphate (AZT-MP) (in contrast to other TMPKs such as E.coli, in which it is a good substrate). Inhibition seems to result from the impossibility of magnesium binding. Optimum pH is 7.5-8.5. Inactive below pH 4.6. Highly thermostable. Is half-inactivated at 65 degrees Celsius. Pyrimidine metabolism; dTTP biosynthesis. Homodimer. The LID domain is a solvent-exposed domain that closes over the site of phosphoryl transfer upon ATP binding. Was identified as a high-confidence drug target. Belongs to the thymidylate kinase family.