Heat Shock Protein 90, Co-chaperone p23 (HSP90, Telomerase-Binding Protein p23, Progesterone Receptor Complex p23)

p23 is a 23kD ubiquitous, highly conserved co-chaperone for Hsp90. p23 binds Hsp90 and participates in the folding of a number of cell regulatory proteins (1). p23 is thought to modulate Hsp90 activity in the last stages of the chaperoning pathway and only binds Hsp90 that is in turn bound to ATP which stablizes this state of Hsp90 (1,4). Hsp90 binds both ATP and p23 at its N-terminus (3). p23 was first identified as a component of hsp90 complexes with the progesterone receptor. It has since been observed in hsp90 complexes with such diverse proteins as Fes kinase, Hsf1, telomerase, and hepadnavirus polymerase. p23 has been shown to stabilize hsp90 complexes with progesterone receptor (PR) or glucocorticoid receptor (GR). Although not strictly required for the interaction of these client proteins with hsp90, p23 dramatically increases the proportion of PR or GR in a mature complex able to bind hormone. It has also been indicated that p23 may have a role in the turnover or dissociation of GR-hsp90 complexes. p23 also has the ability to function as a passive chaperone in vitro because it can prevent the aggregation of denatured proteins. In addition, cellular studies indicate that it can modulate the activities of nuclear receptors even after they have been activated and presumed to be dissociated from hsp90 (4). p23 is also a prominent target in leukemic cell apoptosis. In leukemic cells, geldanamycin enhanced p23 cleavage by rendering p23 more susceptible to caspases-3 and -7 and by enhancing chemotherapy-induced caspase activation. p23 is cleaved at Asp142 and Asp145 by caspase-7 and caspase-3, which results in a 17kD fragment. These findings underscore the importance of the Hsp90-complex in antileukemic treatment, and suggest that p23 may have a role in survival signalling (2).\n\nApplications:\nSuitable for use in Western Blotting. Other applications not tested.\n\nRecommended Dilution:\nWestern Blotting: 1:5000\n\nOptimal dilutions to be determined by the researcher.\n\nStorage and Stability:\nMay be stored at 4 degrees C for short-term only. For long-term storage, store at -20 degrees C. Aliquots are stable for at least 12 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.\n\nSold under license from Geron

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SPECIFICATIONS

Catalog Number

H1834-61

Size

25ul

Applications

WB

Hosts

Rabbit

Reactivities

Hum, Mouse, Rat

Form

Supplied as a liquid in PBS, 0.1mM PMSF, 50% glycerol.

P Type

Pab

Purity

Purified by ammonium sulfate precipitation.

References

1. Weaver, A.J., Sullivan, W.P., Felts, S.J., Owen, B.A., Toft, D.O. (2000) J Biol Chem. 275(30): 23045-52. \n2. Gausdal, G., Gjertsen, B.T., Fladmark, K.E., Demol, H., Vandekerckhove, J., Doskeland, S.O. (2004) Leukemia. Oct 14 [Epub ahead of print]. \n3. Zhu, S., Tytgat, J. (2004) FASEB J.18(9): 940-7. \n4. Sullivan, W.P., Owen, B.A., Toft, D.O. (2002) J Biol Chem. 277(48): 45942-8.

Additional Info

Detects an ~23kD protein, corresponding to the apparent molecular mass of p23 on SDS-PAGE Western Blots, in samples from human, mouse and rat origins.