MET28/YIR017C Summary Help

Standard Name MET28
Systematic Name YIR017C
Feature Type ORF, Verified
Description bZIP transcriptional activator in the Cbf1p-Met4p-Met28p complex; participates in the regulation of sulfur metabolism (1 and see Summary Paragraph)
Name Description METhionine requiring
Chromosomal Location
ChrIX:384119 to 383556 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All MET28 GO evidence and references
  View Computational GO annotations for MET28
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Regulators 11 genes
Classical genetics
Large-scale survey
60 total interaction(s) for 53 unique genes/features.
Physical Interactions
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 3
  • FRET: 2
  • Reconstituted Complex: 2
  • Two-hybrid: 10

Genetic Interactions
  • Negative Genetic: 28
  • Positive Genetic: 12

Expression Summary
Length (a.a.) 187
Molecular Weight (Da) 21,590
Isoelectric Point (pI) 10.88
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrIX:384119 to 383556 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1994-12-10
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..564 384119..383556 2011-02-03 1994-12-10
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000001456

MET28, a member of the basic leucine zipper DNA binding factor family, encodes a transcription factor that participates in the regulation of sulfur metabolism (1). Transcriptional activation of the MET gene network, which includes MET28, requires at least five positive trans-acting factors: Cbf1p, Met4p, Met28p, Met31p, and Met32p (2, 3). Of these five factors, Met4p is the only one endowed with transcription activation function, while the other four act by promoting the recruitment of Met4p to the DNA (1, 4, 5, 6, 3).

Cbf1p, Met4p, and Met28p form a heteromeric complex that binds to the 5'-TCACGTG-3' motif found in the 5' upstream regions of the structural and regulatory genes of the sulfur network (1, 4, 2, 6). The leucine zippers of Met4p and Met28p, along with the basic helix-loop-helix domain of Met28p, provide the protein surfaces mediating these interactions (1, 2, 3). Within the complex, Met4p is responsible for transcriptional activation, and Cbf1p is required for DNA recognition and binding. Met28p regulates the formation of the complex, and functions by stimulating the DNA-binding activity of Cbf1p (4, 2). Both Met4p and Met28p bind to DNA only in the presence of Cbf1p, and the presence of Cbf1p and Met4p stimulates the binding of Met28p to DNA (1, 2).

As for the structural genes involved in sulfur amino acid metabolism, the transcription of MET28 is repressed by increases in the intracellular concentration of S-adenosylmethionine (AdoMet), the end product of the sulfur amino acid biosynthesis pathway (2). Transcription of MET28 also strictly depends on Met4p, which is recruited to the promoter region of MET28 through its association with Met28p and either Met31p or Met32p in high molecular weight complexes (6, 3). Both Met31p and Met32p bind to the 5'-AAACTGTGG-3' sequence, which is present at position -145 upstream of MET28 (6). Met28p may be required to stabilize the interaction established between Met4p and both Met31p and Met32p, but it is not essential for such protein-protein interactions (6). Taken together, the dual functions of Met28p and the mechanism underlying the regulation of MET28 reveal the existence of a positive regulatory loop within the sulfur network (5). This loop is expected to increase dynamically the response of the sulfur network when the intracellular concentration of AdoMet is low (3).

Last updated: 2004-11-01 Contact SGD

References cited on this page View Complete Literature Guide for MET28
1) Kuras L, et al.  (1996) A heteromeric complex containing the centromere binding factor 1 and two basic leucine zipper factors, Met4 and Met28, mediates the transcription activation of yeast sulfur metabolism. EMBO J 15(10):2519-29
2) Kuras L, et al.  (1997) Assembly of a bZIP-bHLH transcription activation complex: formation of the yeast Cbf1-Met4-Met28 complex is regulated through Met28 stimulation of Cbf1 DNA binding. EMBO J 16(9):2441-51
3) Rouillon A, et al.  (2000) Feedback-regulated degradation of the transcriptional activator Met4 is triggered by the SCF(Met30 )complex. EMBO J 19(2):282-94
4) Blaiseau PL, et al.  (1997) Met31p and Met32p, two related zinc finger proteins, are involved in transcriptional regulation of yeast sulfur amino acid metabolism. Mol Cell Biol 17(7):3640-8
5) Thomas D and Surdin-Kerjan Y  (1997) Metabolism of sulfur amino acids in Saccharomyces cerevisiae. Microbiol Mol Biol Rev 61(4):503-32
6) Blaiseau PL and Thomas D  (1998) Multiple transcriptional activation complexes tether the yeast activator Met4 to DNA. EMBO J 17(21):6327-36