D-glyceraldehyde 3-phosphate + D-fructose 6-phosphate <=> xylulose 5-phosphate + D-erythrose 4-phosphate

Cytosolic transketolase (TKT) catalyzes the reaction of D-glyceraldehyde 3-phosphate and D-fructose 6-phosphate to form D-erythrose 4-phosphate and D-xylulose 5-phosphate. The active transketolase enzyme is a homodimer with one molecule of thiamine pyrophosphate and magnesium bound to each monomer (Wang et al. 1997).

线粒体转酮酶（Cytosolic transketolase，简称TKT）催化D-甘油醛-3-磷酸和D-果糖-6-磷酸的反应，生成D-赤藓糖-4-磷酸和D-木酮糖-5-磷酸。活性转酮酶酶为同源二聚体，每个单体与一分子硫胺素焦磷酸盐和镁离子结合（Wang等，1997年）。