GAC1/YOR178C Summary Help

Standard Name GAC1 1
Systematic Name YOR178C
Feature Type ORF, Verified
Description Regulatory subunit for Glc7p type-1 protein phosphatase (PP1); tethers Glc7p to Gsy2p glycogen synthase, binds Hsf1p heat shock transcription factor, required for induction of some HSF-regulated genes under heat shock; GAC1 has a paralog, PIG1, that arose from the whole genome duplication (2, 3, 4, 5, 6 and see Summary Paragraph)
Name Description Glycogen ACcumulation 1
Chromosomal Location
ChrXV:670241 to 667860 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 113 cM
Gene Ontology Annotations All GAC1 GO evidence and references
  View Computational GO annotations for GAC1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 12 genes
Classical genetics
Large-scale survey
42 total interaction(s) for 28 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 5
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 8
  • Biochemical Activity: 1
  • Co-purification: 1
  • Reconstituted Complex: 1
  • Two-hybrid: 8

Genetic Interactions
  • Dosage Growth Defect: 3
  • Dosage Rescue: 4
  • Negative Genetic: 3
  • Phenotypic Enhancement: 2
  • Positive Genetic: 2
  • Synthetic Lethality: 1
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 793
Molecular Weight (Da) 88,532
Isoelectric Point (pI) 5.49
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXV:670241 to 667860 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 113 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..2382 670241..667860 2011-02-03 1996-07-31
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 SGDIDS000005704

Gac1p is a regulator of the Glc7p type-1 protein phosphatase (PP1), and functions as a molecular scaffold to tether Glc7p to the Gsy2p glycogen synthase (3). Gsy2p activity is inhibited by phosphorylation, and the Glc7p-Gac1p holoenzyme is required to dephosphorylate and activate Gsy2p (4, 2). Gac1p also binds the Hsf1p heat shock transcription factor, and Gac1p and Glc7p are both required for the induction of some HSF-regulated genes under heat shock (7).

Gac1p contains a conserved GVNK motif of approximately 25 residues that is also found in mammalian type 1 phosphatase targeting subunits (RGI proteins) (8, 9). The GAC1 promoter contains an STRE sequence, and expression of GAC1 is repressed by Ssa1p, Ssa2p, and cAMP-dependent protein kinase (PKA) (10, 11). GAC1 expression is induced during the diauxic transition, beginning when approximately 50% of the available glucose is consumed, and reaches a maximum at the diauxic shift (12). Gac1p abundance increases during growth with the same kinetics as glycogen accumulation (13). Gac1p is phosphorylated in vivo, is hyperphosphorylated in a glc7-1 mutant, and may be a substrate of Cdc28p (13, 5).

gac1 null mutants accumulate decreased levels of glycogen, increased levels of inactive, hyperphosphorylated Gsy2p (3, 13), and also display decreased transcription of some heat shock factor responsive genes during heat shock (7). Overexpression of GAC1 results in increased Gsy2p activity and glycogen accumulation, partial glucose derepression, and increased salt sensitivity (2, 13).

Last updated: 2005-10-07 Contact SGD

References cited on this page View Complete Literature Guide for GAC1
1) Francois JM, et al.  (1992) GAC1 may encode a regulatory subunit for protein phosphatase type 1 in Saccharomyces cerevisiae. EMBO J 11(1):87-96
2) Wu X, et al.  (2001) Characterization of Gac1p, a regulatory subunit of protein phosphatase type I involved in glycogen accumulation in Saccharomyces cerevisiae. Mol Genet Genomics 265(4):622-35
3) Williams-Hart T, et al.  (2002) Protein phosphatase type 1 regulates ion homeostasis in Saccharomyces cerevisiae. Genetics 160(4):1423-37
4) Nigavekar SS, et al.  (2002) Glc8 is a glucose-repressible activator of Glc7 protein phosphatase-1. Arch Biochem Biophys 404(1):71-9
5) Ubersax JA, et al.  (2003) Targets of the cyclin-dependent kinase Cdk1. Nature 425(6960):859-64
6) Byrne KP and Wolfe KH  (2005) The Yeast Gene Order Browser: combining curated homology and syntenic context reveals gene fate in polyploid species. Genome Res 15(10):1456-61
7) Lin JT and Lis JT  (1999) Glycogen synthase phosphatase interacts with heat shock factor to activate CUP1 gene transcription in Saccharomyces cerevisiae. Mol Cell Biol 19(5):3237-45
8) Cheng C, et al.  (1997) Yeast PIG genes: PIG1 encodes a putative type 1 phosphatase subunit that interacts with the yeast glycogen synthase Gsy2p. Yeast 13(1):1-8
9) Francois J and Parrou JL  (2001) Reserve carbohydrates metabolism in the yeast Saccharomyces cerevisiae. FEMS Microbiol Rev 25(1):125-45
10) Geymonat M, et al.  (1998) Ssa1p chaperone interacts with the guanine nucleotide exchange factor of ras Cdc25p and controls the cAMP pathway in Saccharomyces cerevisiae. Mol Microbiol 30(4):855-64
11) Ward MP, et al.  (1995) SOK2 may regulate cyclic AMP-dependent protein kinase-stimulated growth and pseudohyphal development by repressing transcription. Mol Cell Biol 15(12):6854-63
12) Parrou JL, et al.  (1999) Dynamic responses of reserve carbohydrate metabolism under carbon and nitrogen limitations in Saccharomyces cerevisiae. Yeast 15(3):191-203
13) Stuart JS, et al.  (1994) The mutant type 1 protein phosphatase encoded by glc7-1 from Saccharomyces cerevisiae fails to interact productively with the GAC1-encoded regulatory subunit. Mol Cell Biol 14(2):896-905