Design and evaluation of a real-time activity probe for focal adhesion kinase

Jon R. Beck, Xinqi Zhou, Garrett R. Casey, Cliff I. Stains

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Focal adhesion kinase (FAK) has been identified as a potential therapeutic target for the treatment of metastatic cancers. Herein we describe the design, synthesis and optimization of a direct activity sensor for FAK and its application to screening FAK inhibitors. We find that the position of the sensing moiety, a phosphorylation-sensitive sulfonamido-oxine fluorophore, can dramatically influence the performance of peptide sensors for FAK. Real-time fluorescence activity assays using an optimized sensor construct, termed FAKtide-S2, are highly reproducible (Z' = 0.91) and are capable of detecting as little as 1 nM recombinant FAK. Utilizing this robust assay format, we define conditions for the screening of FAK inhibitors and demonstrate the utility of this platform using a set of well-characterized small molecule kinase inhibitors. Additionally, we provide the selectivity profile of FAKtide-S2 among a panel of closely related enzymes, identifying conditions for selectively monitoring FAK activity in the presence of off-target enzymes. In the long term, the chemosensor platform described in this work can be used to identify novel FAK inhibitor scaffolds and potentially assess the efficacy of FAK inhibitors in disease models.

Original languageEnglish (US)
Pages (from-to)62-68
Number of pages7
JournalAnalytica Chimica Acta
StatePublished - Oct 15 2015


  • Fluorescence-based biosensor
  • Focal adhesion kinase
  • Inhibition
  • Kinase activity assay
  • Small molecule screening

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy


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