Autophagy, the process of bulk degradation of cellular proteins through an autophagosomic-lysosomal pathway is important for normal growth control and may be defective in tumor cells. It is involved in the preservation of cellular nutrients under starvation conditions as well as the normal turnover of cytosolic components and is negatively regulated by TOR (Target of rapamycin). LAMP-2, a highly glycosylated protein associated with the lysosome, has recently been shown to be important in autophagy as mice deficient in this protein failed to convert autophagic vacuoles into vacuoles leading to impaired degradation of long-lived proteins. This correlates with the finding that human LAMP-2 deficiency causing Danon’s disease is associated with the accumulation of autophagic material in striated myocytes. LAMP-2 exists in multiple isoforms.
