Bromo-PEG4-bromide, a PEG-based linker for PROTACs, joins two essential ligands crucial for forming PROTAC molecules, enabling selective protein degradation by leveraging the ubiquitin-proteasome system within cells.

PROTACs, or proteolysis-targeting chimeras, are composed of two distinct ligands joined by a linker. One of these ligands binds to a specific protein target, while the other binds to an E3 ubiquitin ligase. When the PROTAC binds to both the target protein and the E3 ligase, it triggers the ubiquitin-proteasome system within cells to degrade the target protein, thereby providing a mechanism for targeted protein degradation.