A nucleotide is an organic compound made up of three subunits: a nucleobase, a five-carbon sugar, and a phosphate group. The sugar component may either be ribose or deoxyribose. A nucleotide is, thus, a nucleoside with a phosphate group. Depending on the number of phosphate groups attached to the sugar moiety, a nucleotide may be called nucleoside monophosphate (if with only one phosphate group), nucleoside diphosphate (with two phosphate groups), or nucleoside triphosphate (when with three phosphate groups).
Depending on the pentose sugar component, a nucleoside may be a ribonucleoside or a deoxyribonucleoside. A ribonucleoside is a nucleoside with a ribose sugar component. Based on the nucleobase component, the ribonucleoside may be adenosine, guanosine, cytidine, uridine, or 5-methyluridine. A deoxyribonucleoside is a nucleoside with a deoxyribose sugar. Similarly, depending on the nucleobase component, a deoxyribonucleoside may be deoxyadenosine, deoxyguanosine, deoxycytidine, thymidine, or deoxyuridine. Also, depending on the nucleobase component, the nucleosides may be grouped into either the “double-ringed” purine or the “single-ringed” pyrimidine.
Cytidine diphosphate (CDP) is a nucleoside phosphate comprised of a ribonucleoside and two phosphate groups. It means it has a ribose as its sugar and two phosphate groups attached. Its nucleoside contains a pyrimidine base, i.e. a cytosine attached to the ribose sugar. It has two phosphate groups attached to the nucleoside. Inside the cells, CDP can be found in the cytoplasm, mitochondria, and nucleus.
Common biological reactions
Common biological reactions
CDP can be derived from cytidine triphosphates (CTPs) by losing one phosphate group and with the catalytic action of the enzyme soluble calcium-activated nucleotidase 1. CDP may also be interconverted to CTP by the action of the enzyme nucleoside diphosphate kinase 6. 1 Cytidine monophosphate (CMP) may also produce CDP though phosphorylating CMP (wherein the phosphate group may be donated by ATP or CTP) to produce cytidine diphosphate (CDP) via the enzyme CMP kinase. Further phosphorylation yields cytidine triphosphate (CTP).
CDP may also be obtained from food. When the diet contains nucleotides, the body degrades them by the action of nucleotidases to produce nucleosides and phosphates. Nucleosides are degraded into their subcomponents (i.e. nucleobases and sugar) by the action of nucleosidases in the lumen of the digestive tract.
CDP is a metabolite involved in the following biological processes:2
- Pyrimidine metabolism
- Beta Ureidopropionase Deficiency
CDP serves an important role in the synthesis of phospholipids, such as those used in cellular membranes.
- Pyrimidine Metabolism: Homo sapiens. (2018). Retrieved from SMPDB.ca website: ://smpdb.ca/view/SMP0000046 Link
- Human Metabolome Database: Showing metabocard for CDP (HMDB0001546). (2019). Retrieved from Hmdb.ca website: http://www.hmdb.ca/metabolites/HMDB0001546
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