Heat Shock Protein 90 alpha, Recombinant, Human (HSP90a)

The 90kD molecular chaperone family comprises several proteins including the 90kD heat shock protein, Hsp90 and the 94kD glucose-regulated protein, grp94 which are major molecular chaperones of the cytosol and of the endoplasmic reticulum. In mammalian cells there are at least two Hsp90 isoforms, Hsp90alpha and Hsp90beta which are encoded by separate genes. The amino acid sequence of human and yeast Hsp90alpha is 85% and 90% homologous to that of Hsp90beta respectively. All known members of the Hsp90 protein family are highly conserved, especially in the N-terminal and C-terminal regions which have been shown to contain independent chaperone sites with different substrate specificity. These ubiquitous and highly conserved proteins account for 1-2% of all cellular proteins in most cells. Hsp90 is part of the cellís powerful network of chaperones to fight the deleterious consequences of protein unfolding caused by non-physiological conditions. However, in the absence of stress, Hsp90 is a necessary component of fundamental cellular processes such as hormone signalling and cell cycle control. In this context, several key regulatory proteins such as steroid receptors, cell cycle kinases involved in signal transduction and p53 have been identified as substrates of Hsp90. It has been suggested that Hsp90 acts as a capacitor for morphological evolution by buffering widespread variation, which may affect morphogenic pathways. Recent studies indicate that when Drosophila Hsp90 buffering is compromised by temperature for example, cryptic variants are expressed and selection can lead to the continued expression of these traits, even if Hsp90 function is restored. Recombinant protein corresponding to human Heat Shock Protein 90 alpha, full length, with C-terminal His tag, expressed in E. coli. (NM_005348). , Molecular Weight: 85.5kD, Specific Activity: Kd of 5.2nM, Assay Conditions: 95ul reaction mix (20mM HEPES, pH 7.3, 50mM potassium chloride, 5mM magnesium chloride, 20mM Na2MoO4, 0.01% Triton X-100, 0.1mg/ml BSA, 2mM DTT, 0-30nM Hsp90a) + 5ul FITC-geldanamycin, Incubate for 4 hrs at 4ºC. Fluorescent polarization measured at RT (Lambda(exc)=485nm, lambda(em)=528nm). Applications: Useful for the study of enzyme kinetics, screening inhibitors, and selectivity profiling. Other applications not tested. Recommended Dilutions: Optimal dilutions to be determined by the researcher. Storage and Stability: Aliquot to avoid repeated freezing and thawing and store at -70°C. Stable for 6 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.