Evidence that the 90-Kilodalton Heat Shock Protein is Associated with Tubulin-Containing Complexes in L Cell Cytosol and in Intact PtK Cells

Sánchez, Edwin R.; Redmond, Tim; Scherrer, Lawrence C.; Bresnick, Emery H.; Welsh, Michael J.; Pratt, William B.

doi:10.1210/mend-2-8-756

Cited by 118 publications

(48 citation statements)

References 26 publications

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“…Alternatively, the role of hsp90 may be more passive in simply maintaining the inactive state of the receptor until hormone-dependent activation occurs. Another possible role of hsp90 has been suggested by Sanchez et al, who observed an association of hsp90 with microtubules (49). They suggested that this represents an intracellular trafficking system for transporting receptors to their sites of action.…”

Section: Discussionmentioning

confidence: 84%

Binding of heat shock proteins to the avian progesterone receptor.

Kost¹,

Smith²,

Sullivan³

et al. 1989

Mol. Cell. Biol.

191

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The protein composition of the avian progesterone receptor was analyzed by immune isolation of receptor complexes and gel electrophoresis of the isolated proteins. Nonactivated cytosol receptor was isolated in association with the 90-kilodalton (kDa) heat shock protein, hsp9O, as has been described previously. A 70-kDa protein was also observed and was shown by Western immunoblotting to react with an antibody specific to the 70-kDa heat shock protein. Thus, two progesterone receptor-associated proteins are identical, or closely related, to heat shock proteins. When the two progesterone receptor species, A and B, were isolated separately in the absence of hormone, both were obtained in association with hsp9O and the 70-kDa protein. However, activated receptor isolated from oviduct nuclear extracts was associated with the 70-kDa protein, but not with hsp9O. A hormone-dependent dissociation of hsp9O from the cytosolic form of the receptor complex was observed within the first hour of in vivo progesterone treatment, which could explain the lack of hsp9O in nuclear receptor complexes. In a cell-free system, hsp9O binding to receptor was stabilized by molybdate but disrupted by high salt. These treatments, however, did not alter the binding of the 70-kDa protein to receptor. Association of the 70-kDa protein with the receptor could be disrupted by the addition of ATP at elevated temperatures (23°C). The receptor-associated 70-kDa protein is an ATP-binding protein, as demonstrated by its affinity labeling with azido[32P]ATP. These results indicate that the two receptor-associated proteins interact with the progesterone receptor by different mechanisms and that they are likely to affect the structure or function of the receptor in different ways.

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Section: Discussionmentioning

confidence: 84%

Binding of heat shock proteins to the avian progesterone receptor.

Kost¹,

Smith²,

Sullivan³

et al. 1989

Mol. Cell. Biol.

191

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“…In cells, they form complexes with each other and additional proteins (20). Therefore, it was important to see whether Hsp 71 and Hsp 86 each bound Taxol independently or by means of bridging proteins (20)(21)(22). Purified bovine Hsc 73, the homolog of Hsp 71 (86% amino acid identity), and pure, recombinant human Hsp 90␣, the homolog of Hsp 86 (99% amino acid identity), were incubated alone or together in the presence of biotinylated Taxol, and the complexes were purified on monomeric avidin-agarose beads.…”

Section: Resultsmentioning

confidence: 99%

Heat shock protein 90 mediates macrophage activation by Taxol and bacterial lipopolysaccharide

Byrd

Bornmann

Erdjument‐Bromage

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

188

134

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“…It has been shown to interact with steroid receptors (6,38,41), with a variety of protein kinases (4,24,25,33), and with actin (18) and tubulin (37). Some evidence exists for its possible function as a protein kinase (9,28), and one report indicates a molecular chaperone activity of hsp90 in protein renaturation in vitro (52).…”

Section: Discussionmentioning

confidence: 99%

Identification of a 60-kilodalton stress-related protein, p60, which interacts with hsp90 and hsp70.

et al. 1993

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Immunoaffinity purification of hsp90 from chick oviduct cytosol reveals two major proteins, hsp70 and a 60-kDa protein (p60), copurifying with hsp90. A similar result is obtained when hsp90 is immunoaffinity purified from chick liver and brain cytosols, avian fibroblasts, and rabbit reticulocyte lysate. This p60 is the same protein previously identified in certain assembly complexes of chick progesterone receptor generated in a cell-free reconstitution system. Tryptic and cyanogen bromide peptide fragments were generated from gel-purified p60, and partial N-terminal sequences were determined from eight peptides. The sequences show a striking similarity to the sequence of a 63-kDa human protein (IEF SSP 3521) whose abundance is increased in MRC-5 fibroblasts following simian virus 40 transformation. A monoclonal antibody was prepared against avian p60; Western immunoblot analysis showed that p60 was present in each of eight chick tissues examined and in each of the human, rat, rabbit, andXenopus tissues tested. Immunoaffinity purifications from both chick oviduct cytosol and rabbit reticulocyte lysate using anti-p60 and anti-hsp70 monoclonal antibodies confirm that there is a relatively abundant complex in these extracts containing hsp90, hsp70, and p60. This complex appears to comprise an important functional unit in the assembly of progesterone receptor complexes.However, judging from the abundance and widespread occurrence of this multiprotein complex, hsp90, hsp70, and p60 probably function interactively in other systems as well.Numerous recent studies (2,7,8,10,34,49,54) have shown that one of the major heat shock proteins, hsp70, functions in an ATP-dependent manner through transient interactions to mediate folding or unfolding of polypeptide chains. Another major heat shock protein, hsp90, is thought to perhaps also function in some capacity related to folding or protein-protein interactions, but its function(s) remains poorly defined (1). Supporting its potential role in protein folding is a recent demonstration that hsp90 enhances renaturation of some proteins in vitro (52). Perhaps the most widely studied interaction of hsp90 is its identity as a stable component of several unactivated steroid receptor complexes (6, 38, 41). For glucocorticoid receptors, hsp90 binding to receptor is required to maintain high-affinity ligand binding (3,26,40), but other steroid receptors that have been examined do not show this same dependency on hsp90. In all hsp90-nuclear receptor complexes, ligand-dependent activation of the receptor DNA-binding ability is accompanied by dissociation of hsp90 (14,17,31,43), and it appears likely that one hsp90 function is to repress DNA binding by receptor.Steroid receptor-hsp9O interactions provide a model for understanding hsp90 function, but exploiting this model has been hindered by the inability to reversibly assemble receptor-hsp90 complexes in vitro. This drawback was recently overcome by establishing certain physicochemical conditions that permit the use of rabbit reticulocyte...

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Evidence that the 90-Kilodalton Heat Shock Protein is Associated with Tubulin-Containing Complexes in L Cell Cytosol and in Intact PtK Cells

Cited by 118 publications

References 26 publications

Binding of heat shock proteins to the avian progesterone receptor.

Binding of heat shock proteins to the avian progesterone receptor.

Heat shock protein 90 mediates macrophage activation by Taxol and bacterial lipopolysaccharide

Identification of a 60-kilodalton stress-related protein, p60, which interacts with hsp90 and hsp70.

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