Defective KHK does not phosphorylate beta-D-fructose

Stable Identifier
R-HSA-5656459
Type
Reaction [transition]
Species
Homo sapiens
Compartment
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Variant KHK (ketohexokinase) protein fails to catalyze the phosphorylation of fructose to yield fructose 1-phosphate (Fru 1-P), the first step of fructose catabolism in the liver. This defect is associated with essential fructosuria, a rare benign condition characterized by elevated urinary fructose levels associated with consumption of fructose. Two missense mutant alleles have been identified in DNA sequencing studies of affected individuals (Bouthron et al. 1994). One, G40R, has no detectable activity. The second, A43T, encodes a protein whose liver ("A") isoform is inactive but whose peripheral ("C") isoform, though thermally unstable, retains some activity (Asipu et al. 2003).

Literature References
PubMed ID Title Journal Year
7833921 Molecular basis of essential fructosuria: molecular cloning and mutational analysis of human ketohexokinase (fructokinase)

Bonthron, DT, Brady, N, Donaldson, IA, Steinmann, B

Hum Mol Genet 1994
12941785 Properties of normal and mutant recombinant human ketohexokinases and implications for the pathogenesis of essential fructosuria

Asipu, A, Hayward, BE, O'Reilly, J, Bonthron, DT

Diabetes 2003
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
ketohexokinase activity of KHK mutant dimers [cytosol]
Physical Entity
Activity
Normal reaction
Disease
Name Identifier Synonyms
carbohydrate metabolic disorder 2978 disorder of carbohydrate transport and metabolism, inborn errors of carbohydrate metabolism, inborn carbohydrate metabolism disorder
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