m-PEG3-Aminooxy is a PEG-based PROTAC linker can be used in the synthesis of PROTACs[1].
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].
[1]. Luo W, et al. Tailored electroactive and quantitative ligand density microarrays applied to stem cell differentiation. J Am Chem Soc. 2010 Mar 3;132(8):2614-21.