Galactokinase (GALK1)
The protein contains 392 amino acids for an estimated molecular weight of 42272 Da.
Major enzyme for galactose metabolism. (updated: April 1, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
No binding partner found
Biological Process
Carbohydrate metabolic process
Galactitol metabolic process
Galactose catabolic process
Galactose catabolic process via UDP-galactose
Galactose metabolic process
Glycolytic process from galactose
Pathogenesis
Small molecule metabolic process
Molecular Function
ATP binding
Carbohydrate kinase activity
Galactokinase activity
Galactose binding
The reference OMIM entry for this protein is 230200
Galactokinase deficiency
Galk deficiency
Galactosemia ii
A number sign (#) is used with this entry because galactokinase deficiency is caused by mutation in the GALK1 gene (604313) on chromosome 17q24. Classic galactosemia (230400) is a distinct disorder caused by mutation in the gene encoding galactose-1-phosphate uridyltransferase (GALT; 606999) on chromosome 9p13.
DESCRIPTION
Galactokinase deficiency is an autosomal recessive disorder which causes cataract formation in children not maintained on a lactose-free diet. Cataract formation is the result of osmotic phenomena caused by the accumulation of galactitol in the lens (Asada et al., 1999).CLINICAL FEATURES
Gitzelmann (1967) reported juvenile cataracts related to galactokinase deficiency in 2 sibs of a consanguineous Gypsy family, Fanconi had previously reported the cases as instances of 'galactose diabetes;' however, GALT activity in red cells was normal. There was no mental retardation. Several close relatives had reduced red cell galactokinase activity, suggesting that they were heterozygotes. Cook et al. (1971) described an affected newborn, ascertained because of hyperbilirubinemia, who had resolution of the cataracts with dietary management. Segal et al. (1979), who studied affected brothers, suggested that mental retardation may occur with galactokinase deficiency. Prachal et al. (1978) associated presenile cataracts with heterozygosity for galactokinase deficiency and galactose-uridyl transferase deficiency. Bosch et al. (2002) reviewed the clinical features of galactokinase deficiency in describing 55 patients in 25 publications. Cataract was reported in most patients. Clinical abnormalities other than cataract were reported in 15 (35%) of 43 cases for which information was available. However, all symptoms were reported infrequently and a causal relationship with the galactokinase deficiency could not be determined. Pseudotumor cerebri is a rare but consistently reported abnormality in this disorder.MOLECULAR GENETICS
In 2 patients with galactokinase deficiency and cataracts, Stambolian et al. (1995) identified 2 different homozygous mutations in the GALK1 gene (604313.0001; 604313.0002). One of the patients had been reported by Pickering and Howell (1972). In affected members of 6 Romani (Gypsy) families from Bulgaria with galactokinase deficiency, Kalaydjieva et al. (1999) identified a homozygous mutation in the GALK1 gene (P28T; 604313.0003). The authors concluded that this mutation was most likely responsible for the galactokinase deficiency in the cases originally described by Gitzelmann (1967). Asada et al. (1999) identified 5 mutations in the GALK1 gene in 7 unrelated Japanese patients with galactokinase deficiency.POPULATION GENETICS
Mayes and Guthrie (1968) found 6 heterozygotes for galactokinase deficiency among 642 persons in Buffalo, N.Y. In Italy, Magnani et al. (1982) estimated the heterozygote frequency to be 1 in 310; 2 persons presumably heterozygous by biochemical criteria were detected among 620 persons studied. ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 230200 was added.
Jan. 28, 2016: Protein entry updated
Automatic update: model status changed
Jan. 24, 2016: Protein entry updated
Automatic update: model status changed