Fig. 9

Photoaffinity based target ID of bromodomain inhibitor (+)-JQ1. a Structure of (+)-JQ1 target ID probe containing diazirine and cyclopropene. NP-1 and 2 are negative probes for control. b Time dependent target ID probe labeled BRD-4 conjugated with TER-Tz (for BD-1 and 2, iEDDA) or TER-azide (for BD-3, CuAAC). FL : in-gel fluorescence scanning. CBB : Coomassie staining. TER : Tetraethyl Rhodamine. c Proteome labeling of live HepG2 cells by BD-2 or BD-3 with or without excess amount of (+)-JQ1. The pull down and immunostaining showed BRD-4 enrichment by target ID probes. d Ven diagram showing number of BD-2 or BD-3 (1 μM) binding proteins. e Target protein validation of newly discovered unknown target proteins. HepG2 proteome was labeled by 1uM BD-2/3. Negative probes and BD-2/3 with excess amount of (+)-JQ1 did not label target proteins. Reprinted with permission from ref 76. Copyright 2014 American Chemical Society