Thymidine monophosphate (TMP), an essential precursor of DNA synthesis, is produced either by de novo synthesis from deoxyuridine monophosphate (dUMP) or from exogenous TdR (thymidine salvage pathway). Plant cells also contain TK1 genes: the Arabidopsis thaliana genome encompasses two TK1 genes ( TK1a and TK1b , also named TK1 and TK2 ), and TK1a and b share 58% identity at the protein level. In this study, we investigate a functional link between nucleotide deficiency, RS, and the nucleoside salvage pathway (NSP) enzymes deoxycytidine kinase (dCK) and thymidine kinase (TK1). Indeed, a phtC + allele in trans restored pyrimidine uptake to an Escherichia coli mutant that lacked all known nucleoside transporters, whereas a phtD + allele did not. We investigated the use of … dar. MG1655 Pathway: salvage pathways of pyrimidine deoxyribonucleotides Detail Level: Minimal Detail Main compounds only All compounds, enzymes Main compound structures All compound structures If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity. Aminopterin, a folic acid antagonist, inhibits the de novo nucleoside biosynthesis pathway. The basic intracellular form of TK1 is a homo dimer with a subunit size of 25 kDa. Thymidine kinase is highly conserved among eukaryotes with the exception of yeast and other fungi, which lack the salvage pathway. In the thymidine salvage pathway, the human and yeast TMPKs catalyze the next step transforming dTMP to dTDP (Jong & Campbell, 1984; Su & Sclafani, 1991). Another thymidine salvage pathway enzyme, thymi-dine phosphorylase (TP, also known as platelet-derived endothelial cell growth factor), catalyzes the revers-ible catabolism of thymidine to form thymine and 2-deoxyribose-1 Hypoxanthine and thymidine supply preformed purines and pyrimidines for DNA synthesis by hybridomas via the salvage pathway that utilizes HGPRT- contributed by the fused spleen cell. Here, we identified the single TK of maize (Zea mays), denoted CPTK1, as necessary in the replication of the plastidial genome (cpDNA), demonstrating the essential function of the salvage pathway during chloroplast biogenesis. Deficiency in thymidine kinase 2 (TK2) or p53 inducible ribonucleotide reductase small subunit (p53R2) is associated with tissue specific mitochondrial DNA (mtDNA) depletion. The enzymes of the search input Search input auto suggest Abstract Thymidine kinase (TK) is a key enzyme of the salvage pathway that recycles thymidine nucleosides to produce deoxythymidine triphosphate. The dTMP serves as a substrate for DNA polymerase during viral DNA replication. It is therefore primarily a marker of thymidine salvage pathway activity and has been correlated with standard markers of proliferation such as Ki-67 in some cancers ( 5 ). Thymidine Kinase 1 is involved in the DNA synthesis via the metabolic salvage pathway. Multiple myeloma cells may be deficient in deoxycytidine kinase Similarly, the salvage pathway for pyrimidine synthesis uses the substrate deoxythymidine to form thymidine monophosphate using the enzyme thymidine kinase. The observation that thymidine can rescue cells while deoxycytidine is incapable suggests a defect in one branch of the deoxyribonucleoside salvage pathway. 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