Assay Method Information

Assay Name:  IMAP (Immobilized Metal Ion Affinity-Based Fluorescence Polarization) Assay
Description:  EGFR enzyme activity is measured using the IMAP (immobilized metal ion affinity-based fluorescence polarization) assay as outlined below.EGFR enzyme (Invitrogen catalog #PR7295B), is diluted to 2.5 μg/mL in KR buffer (10 mM Tris-HCl, 10 mM MgCl2, 0.01% Tween-20, 0.1% NaN3, 1 mM DTT, 2 mM MnCl2, pH 7.5).Serial dilution log 10 from 1 mM to 31.6 nM of test compounds are made in 100% DMSO. The dilutions in DMSO are then diluted 25-fold in KR-buffer of which 5 μL is used in the assay, leading to a final compound concentration range in the assay from 10 μM to 0.316 nM.The assay is performed as follows: 5 μL/well of test compound in KR buffer (final DMSO concentration in the assay is 1%) is mixed with 5 l/well of 2.5 μg/mL EGFR enzyme (final concentration in the assay is 625 ng/mL). Test compounds and EGFR enzyme are pre-incubated 60 min at room temperature, before adding 5 μL/well of 200 nM Fluorescein labeled substrate peptide (PDGFR-tide substrate peptide RP7084, Molecular Devices) in KR-buffer. Final peptide substrate concentration in assay is 50 nM. The kinase assay is started by adding 5 L/well of 8 μM ATP in KR-buffer (final ATP concentration is 2 μM, Km ATP in EGFR IMAP assay). Following incubation for 60 min at room temperature in the dark the enzyme reaction is stopped by adding 40 μL/well IMAP Progressive Binding Solution (according to suppliers (Molecular Devices) protocol using 20% 1× buffer A and 80% 1× buffer B with 600× diluted beads). After 60 min incubation at room temperature in the dark the FP signal is read. Fluorescence at 535 nm is measured using parallel and perpendicular filters to determine differences in rotation due to binding of the phosphorylated substrate peptide to the beads. Values are calculated as percentage of the difference in readout (ΔmPi) of the controls with and without ATP.
Affinity data for this assay
 

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