Catalyzes the rate-limiting step of the oxidative pentose-phosphate pathway, which represents a route for the dissimilation of carbohydrates besides glycolysis. The main function of this enzyme is to provide reducing power (NADPH) and pentose phosphates for fatty acid and nucleic acid synthesis. D-glucose 6-phosphate + NADP(+) = 6-phospho-D-glucono-1,5-lactone + H(+) + NADPH Carbohydrate degradation; pentose phosphate pathway; D-ribulose 5-phosphate from D-glucose 6-phosphate (oxidative stage): step 1/3. Homotetramer; dimer of dimers (PubMed:24769394, PubMed:10745013, PubMed:15858258). Interacts with SIRT2; the interaction is enhanced by H(2)O(2) treatment (PubMed:24769394). Isoform Long is found in lymphoblasts, granulocytes and sperm. Acetylated by ELP3 at Lys-403; acetylation inhibits its homodimerization and enzyme activity. Deacetylated by SIRT2 at Lys-403; deacetylation stimulates its enzyme activity. The sequence shown is that of variant B, the most common variant. The disease is caused by variants affecting the gene represented in this entry. Deficiency of G6PD is associated with hemolytic anemia in two different situations. First, in areas in which malaria has been endemic, G6PD-deficiency alleles have reached high frequencies (1% to 50%) and deficient individuals, though essentially asymptomatic in the steady state, have a high risk of acute hemolytic attacks. Secondly, sporadic cases of G6PD deficiency occur at a very low frequencies, and they usually present a more severe phenotype. Several types of NSHA are recognized. Class-I variants are associated with severe NSHA; class-II have an activity <10% of normal; class-III have an activity of 10% to 60% of normal; class-IV have near normal activity. Binds two molecules of NADP. The first one is a cosubstrate (bound to the N-terminal domain), the second is bound to the C-terminal domain and functions as a structural element. Belongs to the glucose-6-phosphate dehydrogenase family. Truncated N-terminus. G6PD mutation database