nucleoside kinase activity
Definition
Target type: molecularfunction
Catalysis of the reaction: ATP + nucleoside = ADP + nucleoside monophosphate. [GOC:ai]
Nucleoside kinase activity is a fundamental molecular function that plays a crucial role in the metabolism and utilization of nucleosides, the building blocks of nucleic acids (DNA and RNA). This enzymatic activity catalyzes the phosphorylation of nucleosides, converting them into nucleoside monophosphates (NMPs). NMPs are essential intermediates in the biosynthesis of nucleotides, the monomers that assemble into DNA and RNA.
Nucleoside kinases exhibit substrate specificity, meaning they typically act on a limited range of nucleosides. For example, some kinases may preferentially phosphorylate adenosine, while others may specifically phosphorylate guanosine. This specificity is determined by the enzyme's active site, which interacts with the specific nucleoside and facilitates the transfer of a phosphate group from a donor molecule, such as ATP, to the nucleoside.
The phosphorylation reaction catalyzed by nucleoside kinases is crucial for several biological processes, including:
* **Nucleotide biosynthesis:** NMPs produced by nucleoside kinases are essential precursors for the synthesis of nucleotides, which are required for DNA replication, RNA transcription, and various metabolic pathways.
* **Cellular signaling:** Some nucleoside monophosphates, such as cyclic AMP (cAMP) and cyclic GMP (cGMP), act as second messengers in intracellular signaling pathways, regulating diverse cellular processes.
* **Regulation of nucleoside levels:** Nucleoside kinases help maintain appropriate levels of nucleosides in the cell by converting them into phosphorylated forms, preventing their accumulation and potential toxic effects.
Overall, nucleoside kinase activity is a vital molecular function that ensures the proper synthesis and regulation of nucleosides and nucleotides, essential for various cellular processes, including DNA replication, RNA transcription, and signaling pathways.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Thymidine kinase 2, mitochondrial | A thymidine kinase 2, mitochondrial that is encoded in the genome of human. [PRO:DNx, UniProtKB:O00142] | Homo sapiens (human) |
| Thymidine kinase 2, mitochondrial | A thymidine kinase 2, mitochondrial that is encoded in the genome of human. [PRO:DNx, UniProtKB:O00142] | Homo sapiens (human) |
Compounds (5)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| cytarabine | beta-D-arabinoside; monosaccharide derivative; pyrimidine nucleoside | antimetabolite; antineoplastic agent; antiviral agent; immunosuppressive agent | |
| thymine arabinoside | thymine arabinoside: selectively inhibits replication of herpes simplex virus | N-glycosyl compound | |
| 5-propyl-2'-deoxyuridine | 5-propyl-2'-deoxyuridine: RN given refers to parent cpd | ||
| sorivudine | organic molecular entity | ||
| 9-arabinofuranosylguanine | 9-arabinofuranosylguanine: RN given refers to (beta)-isomer 9-beta-D-arabinofuranosylguanine : A purine nucleoside in which guanine is attached to arabinofuranose via a beta-N(9)-glycosidic bond. It inhibits DNA synthesis and causes cell death. | beta-D-arabinoside; purine nucleoside | antineoplastic agent; DNA synthesis inhibitor |