PT  - JOURNAL ARTICLE
AU  - Kris Wilson
AU  - Scott P Webster
AU  - John P Iredale
AU  - Xiaozhong Zheng
AU  - Natalie Z Homer
AU  - Nhan Pham
AU  - Manfred Auer
AU  - Damian J Mole
TI  - Detecting Drug-Target Binding in Cells using Fluorescence Activated Cell Sorting Coupled with Mass Spectrometry Analysis
AID  - 10.1101/121988
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 121988
4099  - http://biorxiv.org/content/early/2017/04/03/121988.short
4100  - http://biorxiv.org/content/early/2017/04/03/121988.full
AB  - The assessment of drug-target engagement for determining the efficacy of a compound inside cells remains challenging, particularly for difficult target proteins. Existing techniques are more suited to soluble protein targets. Difficult target proteins include those with challenging in vitro solubility, stability or purification properties that preclude target isolation. Here, we report a novel technique that measures intracellular compound-target complex formation, as well as cellular permeability, specificity and cytotoxicity - the Toxicity-Affinity-Permeability-Selectivity (TAPS) technique. The TAPS assay is exemplified here using human kynurenine 3-monooxygenase (KMO), a challenging intracellular membrane protein target of significant current interest. TAPS confirmed target binding of known KMO inhibitors inside cells. We conclude that the TAPS assay can be used to facilitate intracellular hit validation on most, if not all intracellular drug targets.