重组人 ketohexokinase 蛋白 (Tag Free)

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Ketohexokinase also known as KHK or fructokinase is an enzyme that catalyzes the phosphorylation of fructose to fructose-1-phosphate utilizing ATP in the process. This enzyme has two isoforms: KHK-C and KHK-A with the cytosolic form (KHK-C) being approximately 35 kDa in mass. KHK is expressed at high levels in the liver kidney cortex and small intestine showing its importance for fructose metabolism in these tissues. The liver in particular exhibits extensive expression which facilitates the initial step in fructose metabolism.

Biological function summary

Ketohexokinase plays a significant role in the initial stage of fructose metabolism by converting fructose to fructose-1-phosphate. This reaction is a part of the fructose metabolic pathway enabling the use of fructose as an energy source especially in hepatocytes. KHK operates as a monomer and does not form part of any larger protein complex. The enzyme importantly controls the rate of fructose utilization preventing accumulation of free fructose which could lead to metabolic issues.

Pathways

Ketohexokinase belongs to the fructose metabolism pathway which is a subset of the larger carbohydrate metabolism. This enzyme's product fructose-1-phosphate subsequently interacts with aldolase B which is involved in further steps of the glycolysis and gluconeogenesis pathways. Besides aldolase B ketohexokinase's activity influences the balance between fructose and glucose metabolism connecting fructolysis with glycolytic and gluconeogenic pathways.

Dysfunction of ketohexokinase has been linked to hereditary fructose intolerance a condition resulting from a deficiency of aldolase B where the accumulation of fructose-1-phosphate can cause liver damage and hypoglycemia. KHK has also been implicated in metabolic syndrome where excessive fructose consumption exacerbates conditions like insulin resistance and fatty liver disease. The relationship of KHK with metabolic syndrome highlights its interaction with insulin pathways which involves proteins such as insulin receptor substrates that are affected by altered fructose metabolism.