GALK2: Galactokinase 2
A key enzyme in galactose metabolism with potential roles in galactosemia and cancer
Gene Information Card
| Symbol | GALK2 |
|---|---|
| Full Name | galactokinase 2 |
| Gene Type | protein coding |
| Chromosomal Location | 15q21.3 |
| NCBI Gene ID | 2585 ncbi.nlm.nih.gov/gene/2585 |
| Ensembl ID | ENSG00000137807 |
| UniProt ID | Q01415 |
| OMIM ID | 618766 |
| HGNC ID | 4119 |
| Aliases | GK2, GalNAc kinase, N-acetylgalactosamine kinase |
Description
GALK2 (galactokinase 2) encodes an enzyme that catalyzes the phosphorylation of galactose and N-acetylgalactosamine (GalNAc) to galactose-1-phosphate and GalNAc-1-phosphate, respectively. This gene is involved in the galactose metabolism pathway and the hexosamine biosynthetic pathway. Mutations in GALK2 are associated with galactosemia type IV (GALAC4) and have been implicated in various cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Galactosemia type IV (GALAC4) | Loss-of-function mutations in GALK2 impair galactose phosphorylation, leading to accumulation of galactose and galactitol, causing cataracts and other metabolic disturbances. | OMIM #618766; ClinVar |
| Hepatocellular carcinoma | Overexpression of GALK2 has been observed in liver cancer tissues, potentially contributing to altered glycosylation and tumor progression. | COSMIC; NCBI Gene |
| Colorectal cancer | GALK2 expression is upregulated in colorectal tumors, possibly via N-acetylgalactosamine metabolism affecting cell surface glycans. | COSMIC |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | Medium |
| Kidney | 8.3 | Medium |
| Pancreas | 6.1 | Low |
| Small intestine | 5.4 | Low |
| Heart | 3.2 | Low |
| Brain | 1.8 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 (liver cancer) | 15.2 | High expression |
| HEK293 (embryonic kidney) | 9.8 | Moderate expression |
| HeLa (cervical cancer) | 4.5 | Low expression |
| A549 (lung cancer) | 3.1 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.94C>T (p.Arg32Trp) | Missense | Rare | Reduced enzyme activity; associated with galactosemia type IV |
| c.484G>A (p.Gly162Arg) | Missense | Rare | Impaired galactose phosphorylation; pathogenic in ClinVar |
| c.1A>G (p.Met1?) | Start loss | Very rare | Loss of protein expression; likely pathogenic |
Mutation functional classification
Loss of Function (LOF)
Missense mutations (e.g., p.Arg32Trp, p.Gly162Arg) reduce or abolish galactokinase activity, leading to galactosemia type IV.
Gain of Function (GOF)
Not reported in curated databases.
Dominant Negative (DN)
Not reported in curated databases.
View complete mutation data：
Gene Ontology (GO)
| • galactokinase activity (GO:0004335) | • ATP binding (GO:0005524) |
| • kinase activity (GO:0016301) | • galactose metabolic process (GO:0006012) |
| • N-acetylgalactosamine metabolic process (GO:0006041) | • cytoplasm (GO:0005737) |
Pathways
• Galactose metabolism (KEGG: hsa00052)
• Amino sugar and nucleotide sugar metabolism (KEGG: hsa00520)
• Metabolic pathways (KEGG: hsa01100)
Protein Summary
Galactokinase 2 (GALK2) is a 458-amino acid protein that belongs to the GHMP kinase family. It phosphorylates galactose and N-acetylgalactosamine using ATP as a phosphate donor. The enzyme is primarily cytosolic and highly expressed in liver and kidney. Structural studies indicate a conserved ATP-binding domain and a substrate-binding pocket. Defects in GALK2 cause galactosemia type IV, characterized by elevated galactose and cataract formation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| GALK2 Knockout HEK293 Cell Line | EDJ-KQ4678 | Human | 2585 | Details Get a Quote |
| GALK2 Knockout A-549 Cell Line | EDJ-KQ27378 | Human | 2585 | Details Get a Quote |
| GALK2 Knockout HCT 116 Cell Line | EDJ-KQ27379 | Human | 2585 | Details Get a Quote |
| GALK2 Knockout HeLa Cell Line | EDJ-KQ27380 | Human | 2585 | Details Get a Quote |
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