Galactokinase

Function

Galactokinase (GALK) is the enzyme which catalyzes the second step in the Leloir pathway which converts β-D-galactose to glucose 1-phosphate. GALK catalyzes the conversion of α-D-galactose to galactose 1-phosphate^[1].

Disease

Hereditary GALK deficiency is called galactosemia. The symptoms are early onset of cataract and impairment of galactose (gal) metabolism^[2]..

Structural highlights

The 3D structure of human GALK shows the sugar binding active site wedged between the N- and C-termini of the enzyme. The galactose forms with GALK termini residues and in ^[3].

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3D structures of galactokinase

Updated on 04-May-2025

6gr2 - hGALK + ADP + gal - human

7rcl, 7rcm - hGALK (mutant) + ADP + gal
1wuu - hGALK + Mg + AMPPNP + gal
6q3w, 6q8z - hGALK + pyrazine derivative + gal
6q91 - hGALK + benzamide derivative + gal
6q90, 6zgw - hGALK + pyridine derivative + gal
6q3x, 6zfh, 7s49 - hGALK + quinazoline derivative + gal
6zgv, 6zgx, 6zgz, 6zgy, 6zh0 - hGALK + pyrimidine derivative + gal
7s4c - hGALK (mutant) + pyrimidine derivative + gal
6qje - hGALK + imidazole derivative + gal
7ozx - hGALK + inhibitor + gal
2aj4 - GALK + Mg + AMPPNP + gal - yeast
1s4e - GALK + Mg + ADP + gal - Pyrococcus furiosus
2dej, 2dei - GALK + AMPPN derivative + gal - Pyrococcus horikoshii
1pie - GALK + gal - Lactococcus lactis
6tep - BiGALK + Mg + ADP - Bifidobacterium infantis
6ter, 6teq - BiGALK + gal derivative

Se-Met human GALK complex with galactopyranose, AMPPNP and Mg+2 ion (green) (PDB code 1wuu.

Drag the structure with the mouse to rotate

ReferencesReferences

↑ Holden HM, Thoden JB, Timson DJ, Reece RJ. Galactokinase: structure, function and role in type II galactosemia. Cell Mol Life Sci. 2004 Oct;61(19-20):2471-84. doi: 10.1007/s00018-004-4160-6. PMID:15526155 doi:http://dx.doi.org/10.1007/s00018-004-4160-6
↑ Timson DJ, Reece RJ. Functional analysis of disease-causing mutations in human galactokinase. Eur J Biochem. 2003 Apr;270(8):1767-74. PMID:12694189
↑ Thoden JB, Timson DJ, Reece RJ, Holden HM. Molecular structure of human galactokinase: implications for type II galactosemia. J Biol Chem. 2005 Mar 11;280(10):9662-70. Epub 2004 Dec 7. PMID:15590630 doi:10.1074/jbc.M412916200

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

Michal Harel, Alexander Berchansky

[1] Holden HM, Thoden JB, Timson DJ, Reece RJ. Galactokinase: structure, function and role in type II galactosemia. Cell Mol Life Sci. 2004 Oct;61(19-20):2471-84. doi: 10.1007/s00018-004-4160-6. PMID:15526155 doi:http://dx.doi.org/10.1007/s00018-004-4160-6

[2] Timson DJ, Reece RJ. Functional analysis of disease-causing mutations in human galactokinase. Eur J Biochem. 2003 Apr;270(8):1767-74. PMID:12694189

[3] Thoden JB, Timson DJ, Reece RJ, Holden HM. Molecular structure of human galactokinase: implications for type II galactosemia. J Biol Chem. 2005 Mar 11;280(10):9662-70. Epub 2004 Dec 7. PMID:15590630 doi:10.1074/jbc.M412916200

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