HXK2/YGL253W Summary 
HXK2 BASIC INFORMATION
| Standard Name | HXK2 1 |
|---|---|
| Systematic Name | YGL253W |
| Alias | HEX1 , HKB , SCI2 |
| Feature Type | ORF, Verified |
| Description | Hexokinase isoenzyme 2 that catalyzes phosphorylation of glucose in the cytosol; predominant hexokinase during growth on glucose; functions in the nucleus to repress expression of HXK1 and GLK1 and to induce expression of its own gene (2, 3 and see Summary Paragraph) 
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| Name Description | HXK2 |
| GO Annotations | All HXK2 GO evidence and references |
|---|---|
| View Computational GO annotations for HXK2 | |
| Molecular Function | |
| Manually curated | |
| Biological Process | |
| Manually curated | |
| High-throughput | |
| Cellular Component | |
| Manually curated |
| Pathways |
|---|
| Mutant Phenotype | All HXK2 Phenotype details and references |
|---|---|
| Classical genetics | |
| null |
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| reduction of function | |
| Large-scale survey | |
| null |
| Interactions | HXK2 All interactions details and references |
|---|---|
| 83 total interaction(s) for 55 unique genes/features. | |
| Physical Interactions |
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| Genetic Interactions |
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| External Links | All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | UniProtKB |
|---|
| Primary SGDID | S000003222 |
|---|
HXK2 RESOURCES
| SGD ORF map | GBrowse |
|---|---|
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Click on histogram for expression summary
Expression Summary
ADDITIONAL INFORMATION for HXK2
SUMMARY PARAGRAPH for HXK2
The first irreversible step in the intracellular metabolism of glucose involves the phosphorylation of glucose at C6. In Saccharomyces cerevisiae, this can be catalysed by three enzymes, namely the hexokinases Hxk1p and Hxk2p and the glucokinase Glk1p (4, 5, 3). All three proteins are involved in the uptake of glucose (6), however Hxk2p appears to play the main role during glucose phosphorylation in vivo, because it is the predominant isoenzyme during growth on glucose (4, 3). The HXK2 gene is expressed when yeast cells are grown on a fermentable medium using glucose, fructose or mannose as a carbon source (6, 7). When cells are shifted to a non-fermentable carbon source, the HXK2 gene is repressed and the HXK1 and GLK1 genes are rapidly de-repressed (8, 2).
Hxk2p is predominantly found in the cytosol where it is a key enzyme in glycolysis. However, Hxk2p is also found in the nucleus where it is required for the glucose-induced repression of several genes, including HXK1 and GLK1, and for glucose-induced expression of its own gene, HXK2 (2, 9, 10, 11). Interestingly, Hxk2p also plays a role in replicative cell aging because deletion of HXK2 significantly enhances yeast longevity (12).
HXK1, HXK2, and GLK1 homologs have been identified in fission yeast, rice, arabidopsis, and mammals (13, 14, 15). In pancreatic cells, human glucokinase/hexokinase IV (GCK/HK4; OMIM), a functional homolog of S. cerevisiae genes HXK1, HXK2, and GLK1, acts as a glucose sensor and is involved in regulating insulin secretion. Mutations in GCK/HK4 have been associated with the diseases, familial hyperinsulinemic hypoglycemia-3 (OMIM) and the form of late-onset noninsulin-dependent diabetes mellitus known as type II maturity-onset diabetes of the young (OMIM) (16).
Last updated: 2006-11-29
REFERENCES CITED ON THIS PAGE [View Complete Literature Guide for HXK2]
| 1) | Link, A. and Olson, M. (1989) Personal Communication, Mortimer Map Edition 10 |
| 2) | Rodriguez A, et al. (2001) The hexokinase 2 protein regulates the expression of the GLK1, HXK1 and HXK2 genes of Saccharomyces cerevisiae. Biochem J 355(Pt 3):625-31 |
| 3) | Bianconi ML (2003) Calorimetric determination of thermodynamic parameters of reaction reveals different enthalpic compensations of the yeast hexokinase isozymes. J Biol Chem 278(21):18709-13 |
| 4) | Walsh RB, et al. (1983) Cloning of genes that complement yeast hexokinase and glucokinase mutants. J Bacteriol 154(2):1002-4 |
| 5) | Clifton D, et al. (1993) Functional studies of yeast glucokinase. J Bacteriol 175(11):3289-94 |
| 6) | Bisson LF and Fraenkel DG (1983) Involvement of kinases in glucose and fructose uptake by Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 80(6):1730-4 |
| 7) | De Winde JH, et al. (1996) Differential requirement of the yeast sugar kinases for sugar sensing in establishing the catabolite-repressed state. Eur J Biochem 241(2):633-43 |
| 8) | Lobo Z and Maitra PK (1977) Physiological role of glucose-phosphorylating enzymes in Saccharomyces cerevisiae. Arch Biochem Biophys 182(2):639-45 |
| 9) | Gancedo JM (1998) Yeast carbon catabolite repression. Microbiol Mol Biol Rev 62(2):334-61 |
| 10) | Johnston M (1999) Feasting, fasting and fermenting. Glucose sensing in yeast and other cells. Trends Genet 15(1):29-33 |
| 11) | Randez-Gil F, et al. (1998) Hexokinase PII has a double cytosolic-nuclear localisation in Saccharomyces cerevisiae. FEBS Lett 425(3):475-8 |
| 12) | Kaeberlein M, et al. (2005) Genes determining yeast replicative life span in a long-lived genetic background. Mech Ageing Dev 126(4):491-504 |
| 13) | Petit T, et al. (1996) Schizosaccharomyces pombe possesses an unusual and a conventional hexokinase: biochemical and molecular characterization of both hexokinases. FEBS Lett 378(2):185-9 |
| 14) | Cho JI, et al. (2006) Structure, expression, and functional analysis of the hexokinase gene family in rice (Oryza sativa L.). Planta 224(3):598-611 |
| 15) | Miller S, et al. (2007) Kinetic and proteomic analyses of S-nitrosoglutathione-treated hexokinase A: consequences for cancer energy metabolism. Amino Acids 32(4):593-602 |
| 16) | Mayordomo I and Sanz P (2001) Human pancreatic glucokinase (GlkB) complements the glucose signalling defect of Saccharomyces cerevisiae hxk2 mutants. Yeast 18(14):1309-16 |
