Affinity Purification of Protein Kinases that Adopt a Specific Inactive Conformation

Several protein kinases have been characterized in a specific inactive form called the DFG-out conformation. Unlike the active conformation which is conserved in all kinases, the inactive DFG-out conformation appears to be accessible to only certain kinases. This inactive conformation has been successfully targeted with highly selective kinase inhibitors, including the cancer drugs imatinib and sorafenib. However, the structural and sequence requirements for adopting this conformation are still poorly understood. Here, we describe a general method for enriching DFG-out adopting kinases from cell lysates with an affinity resin that contains a general ligand that specifically recognizes this inactive form.