Small bioactive molecules designed to be probes as baits "fishing out" cellular targets: Finding the fish in the proteome sea

Nowadays, therapy target discovery has engaged researchers' attention and interest on account of its important role in drug discovery, and great strides have been made in target identification. Protein classes are regarded as drug targets in this article since majority of targets consist of proteins such as enzymes, proteases, kinases and so on. Based on versatile actions and potential of translational value in clinic medications, small molecule designed to be a probe as a bait can be used in "fishing out" the targets in entire human-proteome sea. Small molecule and the protein actually are ligand and receptor, respectively, and the interaction between them is significant in interrogating drug potency, off-target discovery, some undesirable side-effects and functions of proteins. This review summarizes the components of the probe composed of small molecule and other units, as well as their respective functions in incorporation into targets. Additionally, some published applications employing the strategies of bi- or tri-functional probes are also listed.