fosfoglukoseisomeraasin

Fosfoglukoseisomeraasi, also known as glucose-6-phosphate isomerase (GPI) or phosphoglucose isomerase, is an enzyme that catalyzes the interconversion of glucose-6-phosphate and fructose-6-phosphate. This reaction is a crucial step in both glycolysis and gluconeogenesis, central metabolic pathways involved in energy production and glucose synthesis, respectively.

In glycolysis, GPI facilitates the isomerization of glucose-6-phosphate to fructose-6-phosphate. This step is important because it rearranges the structure of the sugar, preparing it for further phosphorylation and cleavage in subsequent reactions. Conversely, in gluconeogenesis, the enzyme catalyzes the reverse reaction, converting fructose-6-phosphate back to glucose-6-phosphate, which is then dephosphorylated to free glucose.

GPI is found in various organisms, including bacteria, plants, and animals. In humans and other mammals, it is located in the cytoplasm and is also known to function as a moonlighting protein, meaning it has additional roles beyond its enzymatic activity. One such non-enzymatic function is its involvement in cell adhesion and motility, where it can be found on the cell surface.

The enzyme belongs to the family of isomerases. Its activity is essential for cellular energy metabolism, and mutations in the gene encoding GPI can lead to certain metabolic disorders, although these are relatively rare. The enzyme's dual role as a metabolic enzyme and a cell surface protein highlights its multifaceted importance in cellular biology.