title: Alternative assay formats to identify diverse inhibitors of protein kinases.
abstract: BACKGROUND
  Many protein kinases are targets for inhibition during drug discovery. Most first generation inhibitors bind at a site used by the purine moiety of ATP and were discovered in assays following inhibition of activated forms of protein kinases, often using model substrates. This approach presents challenges due to competition by ATP and ADP inside cells, achieving selectivity and securing intellectual property.
  
  
  OBJECTIVE
  To illustrate how increasingly diverse compounds are being identified in assays that target alternative forms of the protein kinase, such as forms with induced conformation changes or where binding occurs at other locations.
  
  
  METHODS
  We review how alternative formats for isolated protein assays may be based on binding rather than catalysis, or include non-activated kinase or physiological substrate.
  
  
  CONCLUSIONS
  Future kinase assays will be designed to detect diverse inhibitors that use a wider, or different, range of binding sites.
authors.affiliation: Singh Consultancy, Shire Home, 4 Grason Avenue, Wilmslow, SK9 2PN, UK +44 0 1625 524 658 ; pirthipal@singh-consultancy.co.uk.
authors.forename: Pirthipal
authors.initials: P
authors.lastname: Singh
authors.forename: Walter Hj
authors.initials: WH
authors.lastname: Ward