Conformational Dynamics of FERM-Mediated Autoinhibition in Pyk2 Tyrosine Kinase

Pyk2 is a non-receptor tyrosine kinase that evolved from gene duplication of focal adhesion kinase (FAK) and subsequent functional specialization in the brain and hemopoietic cells. Pyk2 shares a domain organization with FAK, with an N-terminal regulatory FERM domain adjoining the kinase domain. FAK regulation involves integrin-mediated membrane clustering to relieve autoinhibitory interactions between FERM and kinase domains. Pyk2 regulation remains cryptic, involving Ca²⁺ influx and protein scaffolding. While the mechanism of the FAK FERM domain in autoinhibition is well-established, the regulatory role of the Pyk2 FERM is ambiguous. We probed the mechanisms of FERM-mediated autoinhibition of Pyk2 using hydrogen/deuterium exchange mass spectrometry and kinase activity profiling. The results reveal FERM–kinase interfaces that are responsible for autoinhibition. Pyk2 autoinhibition impacts the activation loop conformation. In addition, the autoinhibitory FERM–kinase interface exhibits allosteric linkage with the FERM basic patch conserved in both FAK and Pyk2.