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Gene Review

SNF3  -  Snf3p

Saccharomyces cerevisiae S288c

Synonyms: D1234, High-affinity glucose transporter SNF3, YDL194W
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High impact information on SNF3

  • Recent studies of Saccharomyces cerevisiae revealed sensors that detect extracellular amino acids (Ssy1p) or glucose (Snf3p and Rgt2p) and are evolutionarily related to the transporters of these nutrients [1].
  • This same mutation introduced into SNF3 also causes glucose-independent expression of HXT genes [2].
  • We have identified another apparent glucose transporter, Rgt2p, that is strikingly similar to Snf3p and is required for maximal induction of gene expression in response to high levels of glucose [2].
  • The predicted amino acid sequence shows that SNF3 encodes a 97-kilodalton protein that is homologous to mammalian glucose transporters and has 12 putative membrane-spanning regions [3].
  • We report here the nucleotide sequence of the cloned SNF3 gene [3].

Biological context of SNF3

  • DDSE: downstream targets of the SNF3 signal transduction pathway [4].
  • An additional mechanism for glucose sensing must exist since a strain lacking all four genes (snf3 rgt2 std1 mth1) is still able to regulate SUC2 gene expression in response to changes in glucose concentration [5].
  • The function of another new member of the HXT superfamily, HXT4 (previously identified by its ability to suppress the snf3 delta phenotype; L. Bisson, personal communication), was revealed in experiments that deleted all possible combinations of the five members of the glucose transporter gene family [6].
  • DNA sequence dependent suppressing elements (DDSEs) are regions located in the promoters of yeast glucose transporter (HXT) genes that when present in high copy suppress the snf3 growth defect [4].
  • Expression was elevated to a high level in an rgt1 mutant in the absence of Snf3p suggesting that this DDSE region contains binding sites for the Rgt1p transcriptional repressor/activator [4].

Anatomical context of SNF3

  • In snf3 delta cells expression of HXT6 is constitutive even when the entire repertoire of HXT genes is present and glucose uptake is abundant [7].
  • In this work, we show that glucose-induced activation of plasma membrane H(+)-ATPase from Saccharomyces cerevisiae is strongly dependent on calcium metabolism and that the glucose sensor Snf3p works in a parallel way with the G protein Gpa2p in the control of the pathway [8].
  • We also show that Snf3p could be involved in the control of Pmc1p activity that would regulate the calcium availability in the cytosol [8].

Associations of SNF3 with chemical compounds

  • Disruption of the HXT1 gene resulted in loss of a portion of high-affinity glucose and mannose transport, and wild-type levels of transport required both the HXT1 and SNF3 genes [9].
  • Loss of the SNF3 gene leads to a long-term adaptation phenotype for cells grown in liquid medium at low substrate concentrations in the presence of the respiratory inhibitor, antimycin A [10].
  • In addition, the growth properties of snf3 mutants suggested that they were defective in uptake of glucose and fructose [11].
  • High basal activity of the HXT7 promoter during growth on ethanol required Snf3 as well as other components of the signalling pathway activated by Snf3 [12].

Physical interactions of SNF3

  • A two-hybrid screen revealed that the Mth1 protein interacts with the cytoplasmic tails of the glucose sensors Snf3 and Rgt2 [13].
  • Multicopy HXT4 increases both high and low affinity glucose transport in snf3 strains and increases low and high transport in wild-type strains [14].
  • Multicopy expression of the HXT1 gene restored high-affinity glucose transport to the snf3 mutant, which is deficient in a significant proportion of high-affinity glucose transport [9].
  • The HXT2 gene of the yeast Saccharomyces cerevisiae was identified on the basis of its ability to complement the defect in glucose transport of a snf3 mutant when present on the multicopy plasmid pSC2 [15].
  • Kinetic analysis of glucose uptake showed that the rgt1 and RGT2 suppressors restore glucose-repressible high-affinity glucose transport in a snf3 mutant [16].

Enzymatic interactions of SNF3

  • We present evidences indicating that Snf3p would be the sensor for the internal signal (phosphorylated sugars) of this pathway that would connect calcium signaling and activation of the plasma membrane ATPase [8].
  • Only in the strain with genes HXT1-4 and SNF3 deleted but carrying HXT6/7 were glucose uptake kinetics and invertase activity independent of the presence or concentration of glucose in the growth medium [17].

Regulatory relationships of SNF3

  • Mutations in MTH1 can suppress the raffinose growth defect of a snf3 mutant as well as the glucose fermentation defect present in cells lacking both glucose sensors (snf3 rgt2) [5].
  • A novel signal transduction pathway in Saccharomyces cerevisiae defined by Snf3-regulated expression of HXT6 [7].
  • Similarly, Hxt2p was found to be expressed under low-glucose conditions in an snf3 mutant which does not display high-affinity uptake [18].

Other interactions of SNF3

  • Rgt2p, which along with Snf3p monitors extracellular glucose levels, appears to be the glucose sensor for the glucose-transport-independent pathway [19].
  • Nevertheless the expression of glucose-repressible HXT3 and SNF3 genes is significantly reduced [20].
  • This finding suggests that SNF3 may be involved in the posttranslational regulation of Hxt2p [18].
  • These findings suggest that GRR1 and SNF3 affect glucose transport by distinct pathways [21].
  • The GAL2 protein is related to the yeast glucose transporter encoded by the SNF3 gene, and also to mammalian and bacterial sugar permeases [22].


  1. Competitive intra- and extracellular nutrient sensing by the transporter homologue Ssy1p. Wu, B., Ottow, K., Poulsen, P., Gaber, R.F., Albers, E., Kielland-Brandt, M.C. J. Cell Biol. (2006) [Pubmed]
  2. Two glucose transporters in Saccharomyces cerevisiae are glucose sensors that generate a signal for induction of gene expression. Ozcan, S., Dover, J., Rosenwald, A.G., Wölfl, S., Johnston, M. Proc. Natl. Acad. Sci. U.S.A. (1996) [Pubmed]
  3. The yeast SNF3 gene encodes a glucose transporter homologous to the mammalian protein. Celenza, J.L., Marshall-Carlson, L., Carlson, M. Proc. Natl. Acad. Sci. U.S.A. (1988) [Pubmed]
  4. DDSE: downstream targets of the SNF3 signal transduction pathway. Theodoris, G., Bisson, L.F. FEMS Microbiol. Lett. (2001) [Pubmed]
  5. Std1 and Mth1 proteins interact with the glucose sensors to control glucose-regulated gene expression in Saccharomyces cerevisiae. Schmidt, M.C., McCartney, R.R., Zhang, X., Tillman, T.S., Solimeo, H., Wölfl, S., Almonte, C., Watkins, S.C. Mol. Cell. Biol. (1999) [Pubmed]
  6. Roles of multiple glucose transporters in Saccharomyces cerevisiae. Ko, C.H., Liang, H., Gaber, R.F. Mol. Cell. Biol. (1993) [Pubmed]
  7. A novel signal transduction pathway in Saccharomyces cerevisiae defined by Snf3-regulated expression of HXT6. Liang, H., Gaber, R.F. Mol. Biol. Cell (1996) [Pubmed]
  8. Calcium signaling and sugar-induced activation of plasma membrane H(+)-ATPase in Saccharomyces cerevisiae cells. Trópia, M.J., Cardoso, A.S., Tisi, R., Fietto, L.G., Fietto, J.L., Martegani, E., Castro, I.M., Brandão, R.L. Biochem. Biophys. Res. Commun. (2006) [Pubmed]
  9. The HXT1 gene product of Saccharomyces cerevisiae is a new member of the family of hexose transporters. Lewis, D.A., Bisson, L.F. Mol. Cell. Biol. (1991) [Pubmed]
  10. The C-terminal domain of Snf3p is sufficient to complement the growth defect of snf3 null mutations in Saccharomyces cerevisiae: SNF3 functions in glucose recognition. Coons, D.M., Vagnoli, P., Bisson, L.F. Yeast (1997) [Pubmed]
  11. Null mutations in the SNF3 gene of Saccharomyces cerevisiae cause a different phenotype than do previously isolated missense mutations. Neigeborn, L., Schwartzberg, P., Reid, R., Carlson, M. Mol. Cell. Biol. (1986) [Pubmed]
  12. Glucose-dependent and -independent signalling functions of the yeast glucose sensor Snf3. Dlugai, S., Hippler, S., Wieczorke, R., Boles, E. FEBS Lett. (2001) [Pubmed]
  13. Mth1 receives the signal given by the glucose sensors Snf3 and Rgt2 in Saccharomyces cerevisiae. Lafuente, M.J., Gancedo, C., Jauniaux, J.C., Gancedo, J.M. Mol. Microbiol. (2000) [Pubmed]
  14. High-copy suppression of glucose transport defects by HXT4 and regulatory elements in the promoters of the HXT genes in Saccharomyces cerevisiae. Theodoris, G., Fong, N.M., Coons, D.M., Bisson, L.F. Genetics (1994) [Pubmed]
  15. The HXT2 gene of Saccharomyces cerevisiae is required for high-affinity glucose transport. Kruckeberg, A.L., Bisson, L.F. Mol. Cell. Biol. (1990) [Pubmed]
  16. Dominant and recessive suppressors that restore glucose transport in a yeast snf3 mutant. Marshall-Carlson, L., Neigeborn, L., Coons, D., Bisson, L., Carlson, M. Genetics (1991) [Pubmed]
  17. Glucose sensing and signalling properties in Saccharomyces cerevisiae require the presence of at least two members of the glucose transporter family. Walsh, M.C., Scholte, M., Valkier, J., Smits, H.P., van Dam, K. J. Bacteriol. (1996) [Pubmed]
  18. Expression of high-affinity glucose transport protein Hxt2p of Saccharomyces cerevisiae is both repressed and induced by glucose and appears to be regulated posttranslationally. Wendell, D.L., Bisson, L.F. J. Bacteriol. (1994) [Pubmed]
  19. Two glucose sensing/signaling pathways stimulate glucose-induced inactivation of maltose permease in Saccharomyces. Jiang, H., Medintz, I., Michels, C.A. Mol. Biol. Cell (1997) [Pubmed]
  20. Transcriptional control of yeast plasma membrane H(+)-ATPase by glucose. Cloning and characterization of a new gene involved in this regulation. García-Arranz, M., Maldonado, A.M., Mazón, M.J., Portillo, F. J. Biol. Chem. (1994) [Pubmed]
  21. Altered regulatory responses to glucose are associated with a glucose transport defect in grr1 mutants of Saccharomyces cerevisiae. Vallier, L.G., Coons, D., Bisson, L.F., Carlson, M. Genetics (1994) [Pubmed]
  22. Yeast galactose permease is related to yeast and mammalian glucose transporters. Nehlin, J.O., Carlberg, M., Ronne, H. Gene (1989) [Pubmed]
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