Article Figures & Data
Figures
- Fig 1
Physiological effects of heat shock. Immediate consequences of thermal stress are depicted as described in the text. Relevant proteins are depicted as colored balls. Three response pathways are shown to be induced by heat shock: the CWI (cell wall integrity) pathway, the ESR (environmental stress response), and the HSR (heat shock response). The physiological effects of ceramide and long-chain base synthesis and accumulation after heat shock are unknown.
- Fig 2
Asymmetric distribution of damaged proteins during growth. Budding (predivision) and budded (postdivision) cells are depicted, with the net retention of damaged proteins in the mother cell resulting from Sir2-dependent transport. The two recently described “compartments” of protein aggregation, JUNQ and IPOD, are shown with known or suspected associated chaperones. Ub, ubiquitin; red asterisk, carbonylation or other protein damage; blue squiggle, unfolded protein.
- Fig 3
Hsf1 and Msn2/4, primary modulators of the heat shock response. Dashed lines represent postulated interactions of the Yak1 kinase in the regulation of both Msn2/4 and Hsf1. Red lines indicate regulatory interactions of protein kinase A. P, phosphorylation; STRE, stress response element; HSE, heat shock element.
- Fig 4
Architecture and regulation of yeast Hsf1. Relevant domains of the budding yeast transcription factor are indicated. Dashed lines represent regulatory relationships between the NTA (amino-terminal transactivation domain) and the CE2 (control element 2)/RD (regulatory domain) on the CTA (carboxy-terminal transactivation domain). The serine-rich region within the RD is phosphorylated by unknown kinases to promote the repression of the CTA through CE2. As described in the text, the NTA promotes a transient transcriptional response, whereas the CTA is responsible for sustained responses. DBD, DNA-binding domain; HRA/B/LZ, heptad repeats A and B, also called the leucine zipper; P, phosphorylation.
- Fig 5
The Hsp90 folding cycle. Yeast proteins participating in the Hsp90 folding cycle are indicated. The complexes depicted are from known yeast protein interactions or inferred from in vitro reconstitution experiments with metazoan counterparts, as described in the text. Unfolded client proteins are indicated by the wavy blue line, and the native folded state is labeled. Kinase clients are thought to mature through a Cdc37-specific pathway (kinases), while nearly all other clients proceed through the multichaperone pathway (nonkinases). The cyclophilin homolog Cpr7 (also Cpr6 [see the text]) is a TPR domain-containing protein that competes for binding with other TPR cofactors, including the phosphatase Ppt1, shown by the dashed line.
- Fig 6
The cytosolic disaggregation and refolding machinery. The native protein is shown to be unfolded by heat shock (depicted as a salmon rectangle), which also causes changes in the sHsp oligomerization status. The constitutive Ssa Hsp70 chaperones partner with the J protein Ydj1 and at least one nucleotide exchange factor (NEF) to promote the refolding of disaggregated (Hsp104 pathway) or unfolded but protected (Hsp42 and Hsp26) proteins.
- Fig 7
The ER chaperome. ER chaperones and associated cofactors are depicted, along with their respective roles in ER protein biogenesis. Gray 40S and 60S subunits depict docked ribosomes. S-S, disulfide bond; UPR, unfolded protein response.
- Fig 8
The mitochondrial chaperome. Chaperones and cofactors of the mitochondrion are shown. OM, outer membrane; IM, inner membrane; IMS, intermembrane space; TOM, transporter outer membrane complex; TIM, transporter inner membrane complex.
Tables
- Table 1
Cytosolic chaperones
Class Protein(s) Function(s) Hsp100 Hsp104 Unfoldase; disaggregase Hsp90 Hsp82 Protein maturation, stress inducible Hsc82 Protein maturation, constitutively expressed Hsp90 cochaperone Sti1 Hsp70/Hsp90-organizing protein homolog, TPR containing Cns1 Similar to Sti1, TPR containing Cdc37 Protein kinase folding Sba1 Hsp90 ATPase regulator Cpr6 Immunophilin homolog, TPR containing, stress inducible Cpr7 Immunophilin homolog, TPR containing, constitutively expressed Sgt1 TPR-containing Hsp90 adaptor protein Aha1 Hsp90 ATPase regulator Ppt1 TPR-containing protein phosphatase Hsp70 GRP170 None Hsp110 Sse1 Hsp70 nucleotide exchange, substrate binding, constitutively expressed Sse2 Hsp70 nucleotide exchange, substrate binding, stress inducible Hsp70 Ssa1, Ssa2 Protein folding, translocation, constitutively expressed Ssa3, Ssa4 Protein folding, translocation, stress inducible Ssb1, Ssb2 Nascent-chain folding Hsp70 NEF Fes1 Hsp70 nucleotide exchange Snl1 Hsp70 nucleotide exchange, ER tethered Hsp40/J protein Ydj1 Hsp70 ATPase activator, substrate binding Sis1 Hsp70 ATPase activator, substrate binding Zuo1 Caj1 Hsp70 ATPase activator, substrate binding Djp1 Hsp70 ATPase activator, substrate binding, peroxisomal import Xdj1 Hsp70 ATPase activator, substrate binding Apj1 Hsp70 ATPase activator, substrate binding Jjj1 Hsp70 ATPase activator, ribosome biogenesis Jjj2 Hsp70 ATPase activator Jjj3 Hsp70 ATPase activator Hlj1 Hsp70 ATPase activator, ERAD Cwc23 Hsp70 ATPase activator, mRNA splicing Swa2 Hsp70 ATPase activator, vesicle transport Chaperonin TriC/Cct1–Cct8 Protein folding, cytoskeleton substrates Chaperonin cochaperone Pfd1–Pfd6 Protein folding, cytoskeleton substrates sHSP Hsp42 Antiaggregase Hsp26 Antiaggregase Other Hsp12 Membrane chaperone? - Table 2
Endoplasmic reticulum chaperones
Class Protein Function(s) Hsp100 None Hsp90 None Hsp90 cochaperone None Hsp70 GRP170 Lhs1 Kar2 nucleotide exchange, substrate binding Hsp110 None Hsp70 Kar2 Protein folding, translocation, UPR regulation, karyogamy Hsp70 NEF Sil1 Kar2 nucleotide exchange Hsp40/J protein Sec63 Kar2 ATPase activator, translocation, ER membrane Scj1 Kar2 ATPase activator Jem1 Kar2 ATPase activator, karyogamy, ER membrane Chaperonin None Chaperonin cochaperone None sHSP None Other Calnexin Cne1 Folding of glycosylated proteins Protein disulfide isomerase Pdi1 Protein folding, disulfide redox chemistry Mpd1 Protein folding, disulfide redox chemistry Mpd2 Protein folding, disulfide redox chemistry Eug1 Protein folding, disulfide redox chemistry? Eps1 Protein folding, disulfide redox chemistry?, ER membrane - Table 3
Mitochondrial chaperones
Class Protein Function(s) Hsp100 Hsp78 Unfoldase, disaggregase Hsp90 None Hsp90 cochaperone None Hsp70 GRP170 None Hsp110 None Hsp70 Ssc1 Protein folding, translocation Ssc3 Protein folding, translocation Ssq1 Folding of FeS proteins Hsp70 NEF Mge1 Hsp70 nucleotide exchange Hsp40/J protein Mdj1 Hsp70 ATPase stimulation, translocation Mdj2 Hsp70 ATPase stimulation, translocation Jac1 Ssq1 J-protein partner Pam16 Partner with Pam18, Hsp70 ATPase stimulation, translocation Pam18 Hsp70 ATPase stimulation, translocation Chaperonin Hsp60 Protein folding, translocation Chaperonin cochaperone Hsp10 Partner with Hsp60, protein folding, translocation sHSP None Other Hep1 Ssc1 partner, stabilization Pim1 Proteolysis and degradation
