| Assay Method Information | |
| | In Vitro FRET Assay |
| Description: | In vitro FRET assay was performed to evaluate the ability of select compounds to inhibit IRE1, the results of which are summarized in Table 3. To perform the in vitro FRET assay, 1× complete assay buffer (CAB; 1M DTT, 50 mM sodium citrate pH 7.15, 1 mM magnesium acetate, 0.02% tween 20) was used to dilute SignalChem IRE1α protein to a final concentration of 2 nM. Selected compounds were serially diluted with DMSO in a non-binding black 384-well plate for a total of 15 ul in each well. 2 ul of the serially diluted compound or DMSO control were then added to new wells containing 98 ul of 1×CAB, for a total volume of 100 ul, 10 ul of which were then transferred to wells of a new plate. 5 ul of the diluted IRE1α was then added to each well. 5 ul of a 400 mM XBP1 RNA probe was then added to each well. Fluorescence was then read over 30 minutes in kinetic mode (485/515 nm).Two RNA probes were used, XBP1 wildtype (SEQ ID NO: 2) which is able to be spliced by active IRE1α or XBP1 mutant (SEQ ID NO: 3) which is unable to be spliced. Each probe contained a 5′ 6-FAM modification and a 3′ IOWA Black FQ modification.A second FRET assay was performed to assess ATP-mediated inhibition. In this case, compounds and IRE1α were prepared and combined as discussed above, with the addition of ATP up to 1 mM final concentration. This mixture was incubated at room temperature for 60 minutes and then 5 ul of 400 nM XBP1 wildtype or mutant RNA probe was added. Plates were then read over 30 minutes in kinetic mode (485/515 nm) and rate of fluorescence increase calculated for different compound dilutions to determine IC50. |
| Affinity data for this assay | |
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