We report herein a set of activity-based probes (ABPs; P3-P7) based on various lysine-reactive covalent warheads capable of global profiling of ligandable lysine within BRDs in live cells and animals. Chemoproteomic experiments with P7 by utilizing 2-ethynylbenzaldehyde (EBA) identified 18 endogenous BRDs, thus giving a global landscape of ligandable lysines in BRDs.