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For example, the prefoldin that is used in the formation of actin also transfers α or β tubulin to a cytosolic chaperonin. The prefoldin, however, does not form a ternary complex with tubulin and chaperonin. Once the tubulins are in contact with the chaperonin, the prefoldin automatically lets go and
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of eukaryotic cells. Prefoldin bonds specifically to cytosolic chaperonin protein. This complex of prefoldin and chaperonin then forms molecules of actin in the cytosol. The prefoldin acts as a transporter molecule that transports bound, unfolded target proteins to the chaperonin (C-CPN) molecule.
219:
protein necessary for actin folding. After gel filtration of the actin, the actin complex, consisting of actin and its bonded proteins, began to form and the molecular weight of the complex was observed. Gel electrophoresis was used to analyze the protein complex, the complex formed a single band
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found in the domains of eukarya and archaea. Prefoldin acts in combination with other molecules to promote protein folding in cells where there are many other competing pathways for folding. Chaperone proteins perform non-covalent assembly of other polypeptide-containing structures
182:. Actin accounts for 5-10% of all protein found in eukaryotic cells, which therefore means that prefoldin is quite prevalent in the cells. Actin is made of two strings of beads wound round each other and is one of the three main parts of the
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Prefoldin is triggered only to bind to nonnative target proteins in the cytosol so that it will only bind to unfolded proteins. Unlike many other molecular chaperones, prefoldin does not use chemical energy, in the form of
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An archaeal homolog of prefoldin that also functions as a molecular chaperone has been identified. Eukaryotic prefoldin likely evolved from archaea, as it is not present (or has been lost) from bacteria.
240:. The height was calculated at 1.8-2.6 nm. The subunits are arranged by hydrophobic interactions with two β barrels at the center and coiled-coil α helices protruding down from them as if it were a
191:
leaves the active site, due to its high affinity for the chaperonin molecule. Once the prefoldin is in contact with the chaperonin protein, it loses its affinity for the unfolded target protein.
34:. The image was produced by Siegerts, R., Scheufler, C., Moarefi, I. using X-Ray diffraction. The heterohexameric protein complex contains two alpha subunits, and four beta subunits. (
178:. In eukarya however, prefoldins have acquired a more specific function: they are used to establish correct tubular assembly for many tubular proteins, such as
220:
that was excised and ran on an SDS gel. It resolved into five bands, therefore proving that a heterooligomeric protein is used to bind to unfolded actin.
215:. Unfolded labeled β-actin from bovine testes was put into solution. This solution contained an excess of cytosolic chaperonin (C-CPN), a eukaryotic
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to form a chaperone complex and correctly fold other nascent proteins. One of prefoldin's main uses in eukarya is the formation of molecules of
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residues each, while the α subunits contain 140 amino acid residues each. Each subunit was found to have a width of 8.4 nm in the archaea
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467:"Structure of the molecular chaperone prefoldin: unique interaction of multiple coiled coil tentacles with unfolded proteins"
293:"A filamentous molecular chaperone of the prefoldin family from the deep-sea hyperthermophile Methanocaldococcus jannaschii"
232:
Prefoldin is a hetero hexameric protein consisting of two α subunits and four β subunits. The beta subunits contain 120
416:
Leroux MR, Fändrich M, Klunker D, Siegers K, Lupas AN, Brown JR, Schiebel E, Dobson CM, Hartl FU (December 1999).
508:"Prefoldin, a jellyfish-like molecular chaperone: functional cooperation with a group II chaperonin and beyond"
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Prefoldin was found by the laboratory of
Nicholas J. Cowan from the Department of Biochemistry at the
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418:"MtGimC, a novel archaeal chaperone related to the eukaryotic chaperonin cofactor GimC/prefoldin"
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The lower "tentacles" of the jellyfish shape is the interface between prefoldin and chaperonin.
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Vainberg IE, Lewis SA, Rommelaere H, Ampe C, Vandekerckhove J, Klein HL, Cowan NJ (May 1998).
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135:. A prefoldin molecule works as a transfer protein in conjunction with a molecule of
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347:"Prefoldin, a chaperone that delivers unfolded proteins to cytosolic chaperonin"
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This is the crystal structure of an archaeal prefoldin taken from the archaeon
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Siegert R, Leroux MR, Scheufler C, Hartl FU, Moarefi I (November 2000).
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In archaea, prefoldins are believed to function in combination with
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Protein, Enzymes, Genes; The interplay of chemistry and
Biology
164:. They are implicated in the folding of most other proteins.
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complexes. It is classified as a heterohexameric molecular
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Oxford
Dictionary of Biochemistry and Molecular Biology
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287:Whitehead TA, Boonyaratanakornkit BB, Höllrigl V,
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506:Sahlan M, Zako T, Yohda M (April 2018).
405:. Cambridge: Cambridge University Press.
267:. Oxford: Oxford University Press. 1997.
211:Medical Center. It was discovered using
403:Molecular Chaperones and Cell Signaling
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32:Methanobacterium thermoautotrophicum
390:. New Haven: Yale University Press.
199:(ATP), to promote protein folding.
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238:Methanococcus thermoautrophicum
1:
484:10.1016/s0092-8674(00)00165-3
364:10.1016/s0092-8674(00)81446-4
155:Prefoldin is one family of
111:(GimC) is a superfamily of
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143:for use in the eukaryotic
524:10.1007/s12551-018-0400-0
23:
434:10.1093/emboj/18.23.6730
197:adenosine triphosphate
309:10.1110/ps.062599907
169:group II chaperonins
512:Biophysical Reviews
209:New York University
401:Pockley A (2005).
386:Fruton JS (1999).
157:chaperone proteins
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297:Protein Science
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184:cytoskeleton
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145:cytoskeleton
131:, including
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50:Identifiers
556:Categories
251:References
234:amino acid
137:chaperonin
242:jellyfish
228:Structure
217:chaperone
203:Discovery
121:chaperone
109:Prefoldin
69:IPR009053
58:Prefoldin
19:Prefoldin
562:Proteins
542:29427249
493:11106732
452:10581246
327:17384227
289:Clark DS
123:in both
115:used in
113:proteins
64:InterPro
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533:6420498
443:1171735
373:9630229
318:2203346
173:de novo
162:in vivo
129:eukarya
125:archaea
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133:humans
101:SUPFAM
55:Symbol
180:actin
141:actin
97:SCOPe
88:SCOP2
538:PMID
489:PMID
471:Cell
448:PMID
369:PMID
351:Cell
323:PMID
127:and
93:1fxk
81:1fxk
76:CATH
41:1FXK
528:PMC
520:doi
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475:103
438:PMC
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359:doi
313:PMC
305:doi
171:in
37:PDB
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