7-Octynoic acid (compound 42) serves as a PROTAC linker for synthesizing various PROTACs, which are composed of two distinct ligands joined by this linker. One ligand interacts with an E3 ubiquitin ligase, while the other binds to the target protein. By leveraging the intracellular ubiquitin-proteasome system, PROTACs selectively degrade target proteins[1].