Reactome | GALM converts beta-D-GAL to alpha-D-GAL

GALM converts beta-D-GAL to alpha-D-GAL

Stable Identifier

R-HSA-9931853

Type

Reaction [transition]

Species

Homo sapiens

Compartment

cytosol

Synonyms

beta-D-galactose=>alpha-D-galactose

ReviewStatus

5/5

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GALM catalyzes the interconversion of alpha- and beta-D-hexose sugars, with preference for galactose over glucose (Timson and Reese, 2003). Gel filtration and x-ray crystallography suggest that human GALM is monomeric like the E. coli enzyme (Timson and Reese, 2003; Thoden et al, 2004). Residues D307 and J176 are critical for enzymatic activity and are conserved across known galactose epimerases (Timson and Reese, 2003; Thoden et al, 2004). Mutations in GALM have been identified in cases of galactosemia, characterized by accumulation of unmetabolized galactose and leading to cataracts and in severe cases to kidney, liver and brain damage. GALM-mediated conversion of beta-Galactose to alpha-galactose is required prior to aGAL phosphorylation by galactokinase (GALK), the first committed step of galactose catabolism (Ai et al, 1995; Timson and Reese, 2003).

Literature References

PubMed ID	Title	Journal	Year
12753898	Identification and characterisation of human aldose 1-epimerase Timson, DJ, Reece, RJ	FEBS Lett.	2003
7542884	Comparison of the enzymatic activities of human galactokinase GALK1 and a related human galactokinase protein GK2 Ai, Y, Basu, M, Bergsma, DJ, Stambolian, D	Biochem Biophys Res Commun	1995
15026423	Molecular structure of human galactose mutarotase Thoden, JB, Timson, DJ, Reece, RJ, Holden, HM	J Biol Chem	2004