Lysosome-Mediated Targeted Protein Degradation: Emerging Chimeric Platforms for Extracellular and Intracellular...

Targeted protein degradation (TPD) is an emerging drug discovery approach aimed at enabling the selective removal of disease-associated proteins. While proteolysis-targeting chimeras (PROTACs) have advanced intracellular degradation via the ubiquitin-proteasome system, their limitation to cytosolic proteins excludes ~40% of the human proteome that is extracellular or membrane-bound. Lysosome-targeting chimeras (LYTACs) address this gap by harnessing lysosomal trafficking receptors, thereby mediating the degradation of extracellular and membrane proteins. More recently, methylarginine-targeting chimeras (MrTACs) have extended lysosomal strategies to certain intracellular targets, bypassing proteasomal dependence. This review critically examines the mechanistic underpinnings, design strategies, and bioanalytical challenges associated with lysosome-mediated degradation platforms. Emphasis is placed on their therapeutic implications, analytical evaluation, and potential for expanding druggable targets. Together, these emerging lysosomal chimeras offer a paradigm shift in TPD, with far-reaching applications in precision medicine and chemical biology.