In enzymology, a glucose-1-phosphate cytidylyltransferase (EC 2.7.7.33) is an enzyme that catalyzes the chemical reaction

CTP + alpha-D-glucose 1-phosphate ${\displaystyle \rightleftharpoons }$ diphosphate + CDP-glucose

Thus, the two substrates of this enzyme are CTP and alpha-D-glucose 1-phosphate, whereas its two products are diphosphate and CDP-glucose.^[1][2]

This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing nucleotide groups (nucleotidyltransferases). The systematic name of this enzyme class is CTP:alpha-D-glucose-1-phosphate cytidylyltransferase. Other names in common use include CDP glucose pyrophosphorylase, cytidine diphosphoglucose pyrophosphorylase, cytidine diphosphate glucose pyrophosphorylase, cytidine diphosphate-D-glucose pyrophosphorylase, and CTP:D-glucose-1-phosphate cytidylyltransferase. This enzyme participates in starch and sucrose metabolism and nucleotide sugars metabolism.^[3]

As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 1TZF and 1WVC.