Boc-gly-PEG3-endo-BCN is a PEG-based PROTAC linker and a cleavable 2-unit PEG ADC linker, utilized in the synthesis of PROTACs[1] and antibody-drug conjugates (ADCs)[2], respectively.

PROTACs contain two different ligands connected by a linker; one is a ligand for an E3 ubiquitin ligase and the other is for the target protein. PROTACs exploit the intracellular ubiquitin-proteasome system to selectively degrade target proteins[1]. ADCs are comprised of an antibody to which is attached an ADC cytotoxin through an ADC linker[2].