HCH1/YNL281W Summary Help

Standard Name HCH1 1
Systematic Name YNL281W
Feature Type ORF, Verified
Description Heat shock protein regulator; binds to Hsp90p and may stimulate ATPase activity; originally identified as a high-copy number suppressor of a HSP90 loss-of-function mutation; role in regulating Hsp90 inhibitor drug sensitivity; GFP-fusion protein localizes to the cytoplasm and nucleus; protein abundance increases in response to DNA replication stress (1, 2, 3, 4, 5, 6 and see Summary Paragraph)
Name Description High-Copy Hsp90 suppressor 1
Chromosomal Location
ChrXIV:108467 to 108928 | ORF Map | GBrowse
Gene Ontology Annotations All HCH1 GO evidence and references
  View Computational GO annotations for HCH1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Regulators 11 genes
Classical genetics
Large-scale survey
42 total interaction(s) for 31 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 12
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 1
  • Co-crystal Structure: 1
  • PCA: 4
  • Protein-RNA: 1
  • Two-hybrid: 4

Genetic Interactions
  • Dosage Growth Defect: 1
  • Dosage Rescue: 2
  • Negative Genetic: 9
  • Positive Genetic: 1
  • Synthetic Growth Defect: 2
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 153
Molecular Weight (Da) 17,246
Isoelectric Point (pI) 4.4
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXIV:108467 to 108928 | ORF Map | GBrowse
Last Update Coordinates: 2005-11-07 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..462 108467..108928 2005-11-07 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 SGDIDS000005225

HCH1 and the closely related gene AHA1 encode cochaperones that regulate the activity of members of the HSP90 family (Hsp82p and Hsc82p in S. cerevisiae; 2, 3). The presence of Aha1p and Hch1p, although not required for ATP hydrolysis, is able to stimulate the ATPase activity of Hsp82p/Hsc82p five- to twelve-fold (2, 3). Aha1p and Hch1p interact with the middle domain of Hsp82p/Hsc82p and promotes a conformational change in the chaperone proteins that enhances their ability to bind ATP (3, 7, 8). Originally identified as a high-copy suppressor of Hch1p is shorter than Aha1p, corresponding to only the Aha1p N-terminus, and also less effective at enhancing Hsp82p/Hsc82p ATPase activity than its longer homolog (1, 2).

Expression of HCH1 is induced by stress, a process mediated by the transcriptional activator Hsf1p which binds to a heat shock element in the HCH1 promoter (2). Although HCH1 is not required for growth under optimal conditions, it is essential for survival in cells under stress (2, 3).

Unlike Aha1p which is highly conserved from yeast to man, Hch1p has only been identified in lower eukaryotes such as Candida albicans (3).

Last updated: 2006-06-30 Contact SGD

References cited on this page View Complete Literature Guide for HCH1
1) Nathan DF, et al.  (1999) Identification of SSF1, CNS1, and HCH1 as multicopy suppressors of a Saccharomyces cerevisiae Hsp90 loss-of-function mutation. Proc Natl Acad Sci U S A 96(4):1409-14
2) Panaretou B, et al.  (2002) Activation of the ATPase activity of hsp90 by the stress-regulated cochaperone aha1. Mol Cell 10(6):1307-18
3) Lotz GP, et al.  (2003) Aha1 binds to the middle domain of Hsp90, contributes to client protein activation, and stimulates the ATPase activity of the molecular chaperone. J Biol Chem 278(19):17228-35
4) Huh WK, et al.  (2003) Global analysis of protein localization in budding yeast. Nature 425(6959):686-91
5) Tkach JM, et al.  (2012) Dissecting DNA damage response pathways by analysing protein localization and abundance changes during DNA replication stress. Nat Cell Biol 14(9):966-76
6) Armstrong H, et al.  (2012) The Co-Chaperone Hch1 Regulates Hsp90 Function Differently than Its Homologue Aha1 and Confers Sensitivity to Yeast to the Hsp90 Inhibitor NVP-AUY922. PLoS One 7(11):e49322
7) Meyer P, et al.  (2004) Structural basis for recruitment of the ATPase activator Aha1 to the Hsp90 chaperone machinery. EMBO J 23(6):1402-10
8) Siligardi G, et al.  (2004) Co-chaperone regulation of conformational switching in the Hsp90 ATPase cycle. J Biol Chem 279(50):51989-98