MDJ1/YFL016C Summary Help

Standard Name MDJ1 1
Systematic Name YFL016C
Feature Type ORF, Verified
Description Co-chaperone that stimulates HSP70 protein Ssc1p ATPase activity; involved in protein folding/refolding in the mitochodrial matrix; required for proteolysis of misfolded proteins; member of the HSP40 (DnaJ) family of chaperones (1, 2, 3, 4 and see Summary Paragraph)
Name Description Mitochondrial DnaJ 1
Chromosomal Location
ChrVI:106236 to 104701 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All MDJ1 GO evidence and references
  View Computational GO annotations for MDJ1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 14 genes
Classical genetics
Large-scale survey
58 total interaction(s) for 50 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 15
  • Affinity Capture-Western: 4
  • Biochemical Activity: 4
  • Co-purification: 1
  • FRET: 1
  • Protein-peptide: 1
  • Reconstituted Complex: 1
  • Two-hybrid: 1

Genetic Interactions
  • Dosage Growth Defect: 1
  • Dosage Rescue: 2
  • Negative Genetic: 19
  • Positive Genetic: 4
  • Synthetic Growth Defect: 2
  • Synthetic Lethality: 2

Expression Summary
Length (a.a.) 511
Molecular Weight (Da) 55,561
Isoelectric Point (pI) 9.95
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrVI:106236 to 104701 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1536 106236..104701 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 SGDIDS000001878

Hsp40/DnaJ is a family of proteins, established by bacterial DnaJ, that regulates Hsp70 chaperone activity. Hsp40s stimulate the intrinsically weak ATPase activity of Hsp70 proteins and facilitate Hsp70 interaction with polypeptide substrates. Hsp70 family members often have multiple Hsp40 partners, and these specific pairings govern Hsp70 chaperone involvement in particular processes (reviewed in 5, 6, and 7). All Hsp40s contain a highly conserved 75-amino acid J domain, which interacts with the ATPase domain of Hsp70 to stimulate ATP hydrolysis. However, there are also other conserved structural domains, and based on the presence or absence of these regions, the Hsp40 family can be divided into three subtypes: type I, type II and type III (a comprehensive overview of the structural features of the different HSP40 subtypes can be found in 7). Sequence analysis of the S. cerevisiae genome has revealed 22 proteins in the Hsp40/DnaJ family: YDJ1, XDJ1, APJ1, SIS1, DJP1, ZUO1, SWA2, JJJ1, JJJ2, JJJ3, CAJ1, CWC23, MDJ1, MDJ2, PAM18, JAC1, JID1, SCJ1, HLJ1, JEM1, SEC63, and ERJ5 (7).

Mdj1p is a type I HSP40 protein that acts as a co-chaperone for Ssc1p in the mitochondrial matrix (reviewed in 7 and 8). Mdj1p is not required for assisting Ssc1p during protein import, but instead participates in folding newly imported and nascent peptides, refolding heat-denatured peptides, and preventing aggregation of unfolded proteins as part of an Ssc1p folding complex (Ssc1p-Mge1p-Mdj1p) (9, 2, 4). Mdj1p is also required for degradation of misfolded proteins, proper mitochondrial DNA inheritance, and maintenance of the activity of mitochondrial DNA polymerase Mip1p (3, 10, 11). Loss of Mdj1p activity results in temperature sensitivity, a respiratory defect, and loss of the mitochondrial genome (1, 10). MDJ1 expression is upregulated upon heat shock via binding of the transcription factor Hsf1p to a non-canonical heat shock element present in the MDJ1 promoter (12). Mdj1p can partially substitute for bacterial DnaJ activity, and homologs from plant (GFA2) and human (DNAJA3) are able to complement an mdj1 null strain (13, 14, 15).

Last updated: 2006-12-19 Contact SGD

References cited on this page View Complete Literature Guide for MDJ1
1) Rowley N, et al.  (1994) Mdj1p, a novel chaperone of the DnaJ family, is involved in mitochondrial biogenesis and protein folding. Cell 77(2):249-59
2) Westermann B, et al.  (1996) Role of the mitochondrial DnaJ homolog Mdj1p as a chaperone for mitochondrially synthesized and imported proteins. Mol Cell Biol 16(12):7063-71
3) Wagner I, et al.  (1994) Molecular chaperones cooperate with PIM1 protease in the degradation of misfolded proteins in mitochondria. EMBO J 13(21):5135-45
4) Kubo Y, et al.  (1999) Two distinct mechanisms operate in the reactivation of heat-denatured proteins by the mitochondrial Hsp70/Mdj1p/Yge1p chaperone system. J Mol Biol 286(2):447-64
5) Qiu XB, et al.  (2006) The diversity of the DnaJ/Hsp40 family, the crucial partners for Hsp70 chaperones. Cell Mol Life Sci 63(22):2560-2570
6) Cyr DM, et al.  (1994) DnaJ-like proteins: molecular chaperones and specific regulators of Hsp70. Trends Biochem Sci 19(4):176-81
7) Walsh P, et al.  (2004) The J-protein family: modulating protein assembly, disassembly and translocation. EMBO Rep 5(6):567-71
8) Voos W and Rottgers K  (2002) Molecular chaperones as essential mediators of mitochondrial biogenesis. Biochim Biophys Acta 1592(1):51-62
9) Horst M, et al.  (1997) Sequential action of two hsp70 complexes during protein import into mitochondria. EMBO J 16(8):1842-9
10) Duchniewicz M, et al.  (1999) Dual role of the mitochondrial chaperone Mdj1p in inheritance of mitochondrial DNA in yeast. Mol Cell Biol 19(12):8201-10
11) Germaniuk A, et al.  (2002) A bichaperone (Hsp70-Hsp78) system restores mitochondrial DNA synthesis following thermal inactivation of Mip1p polymerase. J Biol Chem 277(31):27801-8
12) Tachibana T, et al.  (2002) A novel non-conventional heat shock element regulates expression of MDJ1 encoding a DnaJ homolog in Saccharomyces cerevisiae. J Biol Chem 277(25):22140-6
13) Deloche O, et al.  (1997) Structure-function analyses of the Ssc1p, Mdj1p, and Mge1p Saccharomyces cerevisiae mitochondrial proteins in Escherichia coli. J Bacteriol 179(19):6066-75
14) Christensen CA, et al.  (2002) Mitochondrial GFA2 is required for synergid cell death in Arabidopsis. Plant Cell 14(9):2215-32
15) Lu B, et al.  (2006) Tid1 isoforms are mitochondrial DnaJ-like chaperones with unique carboxyl termini that determine cytosolic fate. J Biol Chem 281(19):13150-8