Focal Adhesion Kinase (FAK)

Focal Adhesion Kinase (FAK) is a 120 kDa tyrosine kinase which become phosphorylated in response to oncogene- and extracellular-matrix integrin-dependent stimulation. Chicken, mouse and human FAK has been isolated and the deduced amino acid sequences showed identity of over 90%. It is expressed in embryonic stem cells, and ubiquitously throughout development, in all adult tissues examined and in many cell lines. The highest expression of FAK is seen in the brain, testes and in osteoclasts. It is distinct from other non-receptor protein tyrosine kinases in that its catalytic domain is flanked by amino- and carboxy-terminal domains of about 400 amino acids each. Also, it does not contain the Src homology 2 or 3 domains, which mediate protein-protein interaction, nor a myristylation site that anchors proteins to the membrane.