CDP is a ribonucleotide formed metabolically from CTP by a phosphatase and converted to dCDP by ribonucleotide reductase (see below). CDP is a component of CDP-diacylglycerol, an important intermediate in glycerophospholipid biosynthesis. CDP is also linked to choline to form CDP-choline in the predominant mechanism of phosphatidylcholine synthesis . Note that though CDP appears in the names of the glycerophospholipid intermediates above, the molecule involved in the reactions making them is CTP, not CDP, so the reactions do not appear below.

Reactions involving CDP:

CTP + H2O <=> CDP + Pi (catalyzed by Phosphatase)

CDP + NADPH <=> dCDP + NADP⁺ (catalyzed by Ribonucleotide Reductase)