Hexokinase I/A is found in all mammalian tissues, and is considered a "housekeeping enzyme," unaffected by most physiological, hormonal, and metabolic changes. Hexokinase II/B constitutes the principal regulated isoenzyme in many cell types and is increased in many cancers. It is the hexokinase found in muscle and heart. Hexokinase II is also located at the mitochondria outer membrane so it can have direct access to ATP. The relative specific activity of hexokinase II increases with pH at least in a pH range from 6.9 to 8.5. Hexokinase III/C is substrate-inhibited by glucose at physiological concentrations. Little is known about the regulatory characteristics of this isoenzyme.
Hexokinase I/A is found in all mammalian tissues, and is considered a "housekeeping enzyme," unaffected by most physiological, hormonal, and metabolic changes. Hexokinase II/B constitu.tes the principal regulated isoenzyme in many cell types and is increased in many cancers. It is the hexokinase found in mu:scle and heart. Hexokinase II is also located at the mitochondria outer membrane so it can have direc!t access to ATP. The relative specific activity of hexokinase II increases with pH at least in a pH range from 6.9 to 85. Hexokinase III/C is substrate-inhibited by glucose at physiological concentrations. Little is known about the regulatory characteristics of this isoenzyme.