Glucose 1 phosphate guanylyltransferase

In enzymology, a glucose-1-phosphate guanylyltransferase (EC 2.7.7.34) is an enzyme that catalyzes the chemical reaction

Thus, the two substrates of this enzyme are GTP and alpha-D-glucose 1-phosphate, whereas its two products are diphosphate and GDP-glucose.

This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing nucleotide groups (nucleotidyltransferases). The systematic name of this enzyme class is GTP:alpha-D-glucose-1-phosphate guanylyltransferase. Other names in common use include GDP glucose pyrophosphorylase, and guanosine diphosphoglucose pyrophosphorylase. This enzyme participates in starch and sucrose metabolism.