Summary: Hsp70 protein
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Hsp70 Edit Wikipedia article
Structure of the ATPase fragment of a 70K heat-shock cognate protein.
The 70 kilodalton heat shock proteins (Hsp70s or DnaK) are a family of conserved ubiquitously expressed heat shock proteins. Proteins with similar structure exist in virtually all living organisms. The Hsp70s are an important part of the cell's machinery for protein folding, and help to protect cells from stress.
Members of the Hsp70 family are very strongly upregulated by heat stress and toxic chemicals, particularly heavy metals such as arsenic, cadmium, copper, mercury, etc. Hsp70 was originally discovered by FM Ritossa in the 1960s when a lab worker accidentally boosted the incubation temperature of Drosophila (fruit flies). When examining the chromosomes, Ritossa found a "puffing pattern" that indicated the elevated gene transcription of an unknown protein. This was later described as the "Heat Shock Response" and the proteins were termed the "Heat Shock Proteins" (Hsps).
The Hsp70 proteins have three major functional domains:
- N-terminal ATPase domain – binds ATP (Adenosine triphosphate) and hydrolyzes it to ADP (Adenosine diphosphate). The NBD consists of two lobes with a deep cleft between them, at the bottom of which nucleotide (ATP and ADP) binds. The exchange of ATP and ADP leads to conformational changes in the other two domains.
- Substrate binding domain – is composed of a 25 kDa β sheet subdomain and a 10 kDa helical subdomain. The β sheet subdomain consists of stranded β sheets with upward protruding loops, as a typical β barrel, which enclose the peptide backbone of the substrate. SBD contains a groove with an affinity for neutral, hydrophobic amino acid residues. The groove is long enough to interact with peptides up to seven residues in length.
- C-terminal domain – rich in alpha helical structure acts as a 'lid' for the substrate binding domain. The helical subdomain consists of five helices, with two helices packed against two sides of the β sheet subdomain, stabilizing the inner structure. In addition, one of the helix forms a salt bridge and several hydrogen bonds to the outer Loops, thereby closing the substrate-binding pocket like a lid. Three helices in this domain form another hydrophobic core which may be stabilization of the "lid". When an Hsp70 protein is ATP bound, the lid is open and peptides bind and release relatively rapidly. When Hsp70 proteins are ADP bound, the lid is closed, and peptides are tightly bound to the substrate binding domain.
Function and regulation
The Hsp70 system interacts with extended peptide segments of proteins as well as partially folded proteins to prevent aggregation, remodel folding pathways, and regulate activity  When not interacting with a substrate peptide, Hsp70 is usually in an ATP bound state. Hsp70 by itself is characterized by a very weak ATPase activity, such that spontaneous hydrolysis will not occur for many minutes. As newly synthesized proteins emerge from the ribosomes, the substrate binding domain of Hsp70 recognizes sequences of hydrophobic amino acid residues, and interacts with them. This spontaneous interaction is reversible, and in the ATP bound state Hsp70 may relatively freely bind and release peptides. However, the presence of a peptide in the binding domain stimulates the ATPase activity of Hsp70, increasing its normally slow rate of ATP hydrolysis. When ATP is hydrolyzed to ADP the binding pocket of Hsp70 closes, tightly binding the now-trapped peptide chain. Further speeding ATP hydrolysis are the so-called J-domain cochaperones: primarily Hsp40 in eukaryotes, and DnaJ in prokaryotes. These cochaperones dramatically increase the ATPase activity of Hsp70 in the presence of interacting peptides.
By binding tightly to partially synthesized peptide sequences (incomplete proteins), Hsp70 prevents them from aggregating and being rendered nonfunctional. Once the entire protein is synthesized, a nucleotide exchange factor (BAG-1 and HspBP1 are among those which have been identified) stimulates the release of ADP and binding of fresh ATP, opening the binding pocket. The protein is then free to fold on its own, or to be transferred to other chaperones for further processing. HOP (the Hsp70/Hsp90 Organizing Protein) can bind to both Hsp70 and Hsp90 at the same time, and mediates the transfer of peptides from Hsp70 to Hsp90.
Hsp70 also aids in transmembrane transport of proteins, by stabilizing them in a partially folded state. It is also known to be phosphorylated  which regulates several of its functions.
Hsp70 proteins can act to protect cells from thermal or oxidative stress. These stresses normally act to damage proteins, causing partial unfolding and possible aggregation. By temporarily binding to hydrophobic residues exposed by stress, Hsp70 prevents these partially denatured proteins from aggregating, and allows them to refold. Low ATP is characteristic of heat shock and sustained binding is seen as aggregation suppression, while recovery from heat shock involves substrate binding and nucleotide cycling. In a thermophile anaerobe (Thermotoga maritima) the Hsp70 demonstrates redox sensitive binding to model peptides, suggesting a second mode of binding regulation based on oxidative stress.
Hsp70 seems to be able to participate in disposal of damaged or defective proteins. Interaction with CHIP (Carboxyl-terminus of Hsp70 Interacting Protein)–an E3 ubiquitin ligase–allows Hsp70 to pass proteins to the cell's ubiquitination and proteolysis pathways.
Finally, in addition to improving overall protein integrity, Hsp70 directly inhibits apoptosis. One hallmark of apoptosis is the release of cytochrome c, which then recruits Apaf-1 and dATP/ATP into an apoptosome complex. This complex then cleaves procaspase-9, activating caspase-9 and eventually inducing apoptosis via caspase-3 activation. Hsp70 inhibits this process by blocking the recruitment of procaspase-9 to the Apaf-1/dATP/cytochrome c apoptosome complex. It does not bind directly to the procaspase-9 binding site, but likely induces a conformational change that renders procaspase-9 binding less favorable. Hsp70 is shown to interact with Endoplasmic reticulum stress sensor protein IRE1alpha thereby protecting the cells from ER stress - induced apoptosis. This interaction prolonged the splicing of XBP-1 mRNA thereby inducing transcriptional upregulation of targets of spliced XBP-1 like EDEM1, ERdj4 and P58IPK rescuing the cells from apoptosis. Other studies suggest that Hsp70 may play an anti-apoptotic role at other steps, but is not involved in Fas-ligand-mediated apoptosis (although Hsp 27 is). Therefore, Hsp70 not only saves important components of the cell (the proteins) but also directly saves the cell as a whole. Considering that stress-response proteins (like Hsp70) evolved before apoptotic machinery, Hsp70's direct role in inhibiting apoptosis provides an interesting evolutionary picture of how more recent (apoptotic) machinery accommodated previous machinery (Hsps), thus aligning the improved integrity of a cell's proteins with the improved chances of that particular cell's survival.
Expression in skin tissue
Both HSP70 and HSP47 were shown to be expressed in dermis and epidermis following laser irradiation, and the spatial and temporal changes in HSP expression patterns define the laser-induced thermal damage zone and the process of healing in tissues. HSP70 may define biochemically the thermal damage zone in which cells are targeted for destruction, and HSP47 may illustrate the process of recovery from thermally induced damage.
Prokaryotes express three Hsp70 proteins: DnaK, HscA (Hsc66), and HscC (Hsc62).
Eukaryotic organisms express several slightly different Hsp70 proteins. All share the common domain structure, but each has a unique pattern of expression or subcellular localization. These are, among others:
- Hsc70 (Hsp73/HSPA8) is a constitutively expressed chaperone protein. It typically makes up one to three percent of total cellular protein.
- Hsp70 (encoded by three very closely related paralogs: HSPA1A, HSPA1B, and HSPA1L) is a stress-induced protein. High levels can be produced by cells in response to hyperthermia, oxidative stress, and changes in pH.
- Binding immunoglobulin protein (BiP or Grp78) is a protein localized to the endoplasmic reticulum. It is involved in protein folding there, and can be upregulated in response to stress or starvation.
- mtHsp70 or Grp75 is the mitochondrial Hsp70.
The following is a list of human Hsp70 genes and their corresponding proteins:
- Mitochondrial import stimulation factor
- Heat shock protein 70 (Hsp70) internal ribosome entry site (IRES)
- Flaherty KM, DeLuca-Flaherty C, McKay DB (August 1990). "Three-dimensional structure of the ATPase fragment of a 70K heat-shock cognate protein". Nature. 346 (6285): 623–8. doi:10.1038/346623a0. PMID 2143562.
- Tavaria M, Gabriele T, Kola I, Anderson RL (April 1996). "A hitchhiker's guide to the human Hsp70 family". Cell Stress Chaperones. 1 (1): 23–8. doi:10.1379/1466-1268(1996)001<0023:AHSGTT>2.3.CO;2. PMC . PMID 9222585.
- Morano KA (October 2007). "New tricks for an old dog: the evolving world of Hsp70". Ann. N. Y. Acad. Sci. 1113: 1–14. doi:10.1196/annals.1391.018. PMID 17513460.
- Ritossa F (1962). "A new puffing pattern induced by temperature shock and DNP in drosophila". Cellular and Molecular Life Sciences (CMLS). 18 (12): 571–573. doi:10.1007/BF02172188.
- Ritossa F (June 1996). "Discovery of the heat shock response". Cell Stress Chaperones. 1 (2): 97–8. doi:10.1379/1466-1268(1996)001<0097:DOTHSR>2.3.CO;2. PMC . PMID 9222594.
- Mayer M P (2010). "Gymnastics of Molecular Chaperones". Cell. 39: 321–331. doi:10.1016/j.molcel.2010.07.012.
- Alireza Mashaghi, Sergey Bezrukavnikov, David P. Minde, Anne S. Wentink, Roman Kityk, Beate Zachmann-Brand, Matthias P. Mayer, Günter Kramer, Bernd Bukau & Sander J. Tans (2016). "Alternative modes of client binding enable functional plasticity of Hsp70". Nature. doi:10.1038/nature20137. PMID 27783598.
- Wegele H, Müller L, Buchner J (2004). "Hsp70 and Hsp90 – a relay team for protein folding". Rev. Physiol. Biochem. Pharmacol. Reviews of Physiology, Biochemistry and Pharmacology. 151: 1–44. doi:10.1007/s10254-003-0021-1. ISBN 978-3-540-22096-1. PMID 14740253.
- Čvoro, Aleksandra; Dundjerski, Jadranka; Trajković, Divna; Matić, Gordana (1999-04-01). "The Level and Phosphorylation of Hsp70 in the Rat Liver Cytosol After Adrenalectomy and Hyperthermia". Cell Biology International. 23 (4): 313–320. doi:10.1006/cbir.1998.0247. ISSN 1095-8355.
- Gao, Tianyan; Newton, Alexandra C. (2002-08-30). "The Turn Motif Is a Phosphorylation Switch That Regulates the Binding of Hsp70 to Protein Kinase C". Journal of Biological Chemistry. 277 (35): 31585–31592. doi:10.1074/jbc.M204335200. ISSN 0021-9258. PMID 12080070.
- Truman, Andrew W.; Kristjansdottir, Kolbrun; Wolfgeher, Donald; Hasin, Naushaba; Polier, Sigrun; Zhang, Hong; Perrett, Sarah; Prodromou, Chrisostomos; Jones, Gary W. (2012-12-07). "CDK-Dependent Hsp70 Phosphorylation Controls G1 Cyclin Abundance and Cell-Cycle Progression". Cell. 151 (6): 1308–1318. doi:10.1016/j.cell.2012.10.051. ISSN 0092-8674. PMC . PMID 23217712.
- Muller, P; Ruckova, E; Halada, P; Coates, P J; Hrstka, R; Lane, D P; Vojtesek, B. "C-terminal phosphorylation of Hsp70 and Hsp90 regulates alternate binding to co-chaperones CHIP and HOP to determine cellular protein folding/degradation balances". Oncogene. 32 (25): 3101–3110. doi:10.1038/onc.2012.314.
- Lüders J, Demand J, Höhfeld J (February 2000). "The ubiquitin-related BAG-1 provides a link between the molecular chaperones Hsc70/Hsp70 and the proteasome". J. Biol. Chem. 275 (7): 4613–7. doi:10.1074/jbc.275.7.4613. PMID 10671488.
- Beere HM, Wolf BB, Cain K, Mosser DD, Mahboubi A, Kuwana T, Tailor P, Morimoto RI, Cohen GM, Green DR (August 2000). "Heat-shock protein 70 inhibits apoptosis by preventing recruitment of procaspase-9 to the Apaf-1 apoptosome". Nat. Cell Biol. 2 (8): 469–75. doi:10.1038/35019501. PMID 10934466.
- Gupta S, Deepti A, Deegan S, Lisbona F, Hetz C, Samali A (July 2010). Kelly, Jeffrey W., ed. "HSP72 Protects Cells from ER Stress-induced Apoptosis via Enhancement of IRE1α-XBP1 Signaling through a Physical Interaction". PLoS Biol. 8 (7): e1000410. doi:10.1371/journal.pbio.1000410. PMC . PMID 20625543.
- Ricaniadis N, Kataki A, Agnantis N, Androulakis G, Karakousis CP (February 2001). "Long-term prognostic significance of HSP-70, c-myc and HLA-DR expression in patients with malignant melanoma". Eur J Surg Oncol. 27 (1): 88–93. doi:10.1053/ejso.1999.1018. PMID 11237497.
- Ramp U, Mahotka C, Heikaus S, Shibata T, Grimm MO, Willers R, Gabbert HE (October 2007). "Expression of heat shock protein 70 in renal cell carcinoma and its relation to tumor progression and prognosis". Histol. Histopathol. 22 (10): 1099–107. PMID 17616937.
- "Heat shock proteins and cancer". HealthValue. Retrieved 2009-05-26.
- Sajjadi AY, Mitra K, Grace M (2013). "Expression of heat shock proteins 70 and 47 in tissues following short-pulse laser irradiation: Assessment of thermal damage and healing" (PDF). Medical Engineering & Physics. 35: 1406–1414. doi:10.1016/j.medengphy.2013.03.011.
- Yoshimune K, Yoshimura T, Nakayama T, Nishino T, Esaki N (May 2002). "Hsc62, Hsc56, and GrpE, the third Hsp70 chaperone system of Escherichia coli". Biochem. Biophys. Res. Commun. 293 (5): 1389–95. doi:10.1016/S0006-291X(02)00403-5. PMID 12054669.
This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.
Hsp70 protein Provide feedback
Hsp70 chaperones help to fold many proteins. Hsp70 assisted folding involves repeated cycles of substrate binding and release. Hsp70 activity is ATP dependent. Hsp70 proteins are made up of two regions: the amino terminus is the ATPase domain and the carboxyl terminus is the substrate binding region.
Internal database links
|SCOOP:||Actin BcrAD_BadFG Hydantoinase_A Ppx-GppA FGGY_C Radial_spoke_3 EutA StbA MreB_Mbl DUF1464 SrfB DDR PilM_2 FtsA DUF4624|
|Similarity to PfamA using HHSearch:||MreB_Mbl FtsA|
External database links
|Transporter classification:||1.A.33 3.A.9|
This tab holds annotation information from the InterPro database.
InterPro entry IPR013126
Heat shock proteins, Hsp70 chaperones help to fold many proteins. Hsp70 assisted folding involves repeated cycles of substrate binding and release. Hsp70 activity is ATP dependent. Hsp70 proteins are made up of two regions: the amino terminus is the ATPase domain and the carboxyl terminus is the substrate binding region [PUBMED:9476895].
Hsp70 proteins have an average molecular weight of 70 kDa [PUBMED:2686623, PUBMED:2944601, PUBMED:3282176]. In most species, there are many proteins that belong to the Hsp70 family. Some of these are only expressed under stress conditions (strictly inducible), while some are present in cells under normal growth conditions and are not heat-inducible (constitutive or cognate) [PUBMED:2143562, PUBMED:2841196]. Hsp70 proteins can be found in different cellular compartments(nuclear, cytosolic, mitochondrial, endoplasmic reticulum, for example).
This entry represents the Hsp70 family, and includes chaperone protein DnaK and luminal-binding proteins.
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
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The actin-like ATPase domain forms an alpha/beta canonical fold. The domain can be subdivided into 1A, 1B, 2A and 2B subdomains. Subdomains 1A and 1B share the same RNAseH-like fold (a five-stranded beta-sheet decorated by a number of alpha-helices). Domains 1A and 2A are conserved in all members of this superfamily, whereas domain 1B and 2B have a variable structure and are even missing from some homologues . Within the actin-like ATPase domain the ATP-binding site is highly conserved. The phosphate part of the ATP is bound in a cleft between subdomains 1A and 2A, whereas the adenosine moiety is bound to residues from domains 2A and 2B.
The clan contains the following 31 members:Acetate_kinase Actin Actin_micro AnmK BcrAD_BadFG Carbam_trans_N DDR DUF1464 DUF2229 EutA FGGY_C FGGY_N FtsA Fumble GDA1_CD39 Glucokinase Hexokinase_1 Hexokinase_2 HGD-D HSP70 Hydant_A_N Hydantoinase_A MreB_Mbl MutL Pan_kinase Peptidase_M22 PilM_2 Ppx-GppA ROK StbA T2SSL
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
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This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.
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Curation and family details
This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.
|Author:||Bateman A, Sonnhammer ELL|
|Number in seed:||27|
|Number in full:||16272|
|Average length of the domain:||416.70 aa|
|Average identity of full alignment:||29 %|
|Average coverage of the sequence by the domain:||81.20 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 17690987 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||18|
|Download:||download the raw HMM for this family|
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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the More....
This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.
How the sunburst is generated
The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, its distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.
In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:
Colouring and labels
Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.
As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.
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There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.
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Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.
Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".
Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
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For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.
The tree shows the occurrence of this domain across different species. More...
We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.
Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.
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For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.
We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.
Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.
We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.
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There are 9 interactions for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the HSP70 domain has been found. There are 254 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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