ABSTRACT
Along with extracellular proteins, certain plasma membrane and vesicular membrane proteins can be delivered to lysosomes through early and late endosomes and subsequently degraded within lysosomes.8,9 Examples of such plasma membrane proteins include the insulin receptor (IR) and epidermal growth factor receptor (EGFR).5,9 Other vesicular proteins delivered to lysosomes for degradation include membrane anchored proteins from the smooth endoplasmic reticulum.5,6 However, the pathway of delivery of such proteins is highly selective, and certain proteins are recycled to the plasma membrane or smooth endoplasmic reticulum (SER) rather than being degraded by lysosomes.9
