In vitro IRAK-1 and IRAK-4 Assay: Purified recombinant IRAK-4 protein was incubated with 250 uM synthetic peptide(KKARFSRFAGSSPSQSSMVAR) in 30 ul of kinase buffer including (20 mM MOPS pH7.2, 25 mM beta glycerol phosphate, 5 mM EGTA, 1 mM sodium orthovanadate, 1 mM DTT, 50 uM ATP, 20 mM MgCl2, 10 uCi gamma-33P, 0.1% BSA) for the indicated time. For purified recombinant IRAK-1 protein kinase assay, 50 uM ATP was used. A 25 ul aliquot of the reaction mixture was transferred on to p81 phosphocellulose squares (Upstate Biotechnology, Lake Placid, N.Y.). The assay squares were washed three times with 0.75% phosphoric acid and once with acetone. Enzyme activity was measured by determining the bound radioactivity by liquid scintillation counting.
In vitro IRAK-1 and IRAK-4 Assay: Purified recombinant IRAK-4 protein was incubated with 250 uM synthetic peptide(KKARFSRFAGSSPSQSSMVAR) in 30 ul of kinase buffer including (20 mM MOPS pH7.2, 25 mM beta glycerol phosphate, 5 mM EGTA, 1 mM sodium orthovanadate, 1 mM DTT, 50 uM ATP, 20 mM MgCl2, 10 uCi gamma-33P, 0.1% BSA) for the indicated time. For purified recombinant IRAK-1 protein kinase assay, 50 uM ATP was used. A 25 ul aliquot of the reaction mixture was transferred on to p81 phosphocellulose squares (Upstate Biotechnology, Lake Placid, N.Y.). The assay squares were washed three times with 0.75% phosphoric acid and once with acetone. Enzyme activity was measured by determining the bound radioactivity by liquid scintillation counting.