High impact information on SNF4

• Loss-of-function mutations in the homologous gene in yeast (SNF4) cause defects in glucose metabolism, including glycogen storage [1].
• We show that SNF4 binds to the SNF1 regulatory domain in low glucose, whereas in high glucose the regulatory domain binds to the kinase domain of SNF1 itself [2].
• Increased dosage of the MSN3 gene restored invertase expression in snf4 mutants and also relieved glucose repression in the wild type [3].
• On the other hand, expression of cNPK5 failed to suppress the growth defect of the snf4 mutant cells in the presence of sucrose and to induce expression of the SUC2 gene [4].
• A 36-kilodalton SNF4 protein is predicted from the nucleotide sequence [5].

Biological context of SNF4

• Finally, cells lacking the gamma subunit of the Snf1 kinase complex encoded by the SNF4 gene exhibited normal regulation of threonine 210 phosphorylation in response to glucose limitation but are unable to phosphorylate Mig1 efficiently [6].
• Derepression studies with CAT3 transformants using a multi-copy plasmid showed over-expression of glyoxylate cycle enzymes [7].
• Genes CAT1 and CAT3 have been isolated by complementation of the cognate mutations after transformation with an episomal plasmid gene library [7].
• The gene SCI1 was cloned and its nucleotide sequence revealed it to be identical to CAT3/SNF4 [8].
• The results obtained are in agreement with the view that the SNF4 gene is involved in the regulation of cell cycle in yeast [9].

Anatomical context of SNF4

• When plasma membrane association of Sip2p is abolished by a mutation that blocks its N-myristoylation, Snf4p is shifted to the nucleus [10].
• No peroxisomes were detected in snf1 and snf4 mutants by immunogold labelling as well as by immunofluorescence [11].

Associations of SNF4 with chemical compounds

• The SNF1 protein kinase and the associated SNF4 protein are required for release of glucose repression in Saccharomyces cerevisiae [12].
• Saccharomyces cerevisiae regulatory genes CAT1 and CAT3 constitute a positive control circuit necessary for derepression of gluconeogenic and disaccharide-utilizing enzymes [13].
• Levels of transcripts of genes encoding catalase A, fatty acid beta-oxidation enzymes and of the PAS1 gene are reduced in snf1 and snf4 mutants on ethanol as well as on oleic acid medium [11].
• These genes were called CAT1, CAT3, and MUR1 and in a mutated form abolished maltose inhibition caused by mutant allele hex2-3 [14].
• The synergistic positive regulatory roles for both the noncatalytic beta and gamma subunits of 5'-AMP-activated protein kinase contrasts with the Snf1p kinase, where only heterodimers of Snf1p and Snf4p seem to be required for maximum kinase activity [15].

Regulatory relationships of SNF4

• In two-hybrid assays, one SNF4 mutation enhances the interaction between Snf4 and Snf1 [16].

Other interactions of SNF4

• To identify components of the SNF1 pathway, we isolated multicopy suppressors of defects caused by loss of SNF4, an activator of the SNF1 kinase [3].
• Moreover, it suppressed Delta snf4 and Delta sip1,Delta sip2,Delta gal83 deficiencies [17].
• These results indicate that SNF4 is required for the induction of SUC2 expression by NPK5, as by SNF1, even if NPK5 is constitutively active in S. cerevisiae [4].
• Mode of action of the qcr9 and cat3 mutations in restoring the ability of Saccharomyces cerevisiae tps1 mutants to grow on glucose [8].
• Moreover, trans-acting factors like ADR1, SNF1 and SNF4, all involved in derepression of various cellular processes, have been demonstrated to affect transcriptional regulation of genes encoding peroxisomal proteins [18].

Analytical, diagnostic and therapeutic context of SNF4

• Deletion of Elc1 resulted in decreased steady-state levels of Snf4 and Pcl6 as indicated by Western blot analysis [19].

References