Hepatic fructokinase (or ketohexokinase) is an enzyme that catalyzes the phosphorylation of fructose to produce fructose-1-phosphate.
ATP + ADP +
ATP + D-fructose â ADP + D-fructose-1-phosphate
Isoforms
In humans, ketohexokinase is encoded by the KHK gene, which produces two isoforms, KHK-A and KHK-C, through alternative splicing.
- KHK-C is primarily expressed in the liver, kidney, and intestine. It has a high affinity for fructose (low K<sub>m</sub>) and is responsible for the majority of fructose metabolism.
- KHK-A is ubiquitously expressed in many tissues at low levels. It has a significantly lower affinity for fructose (high K<sub>m</sub>) compared to the C isoform.
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