Lamp1, short for Lysosomal-associated membrane protein 1, is one of the major proteins in the lysosomal membrane. It is often used as a lysosome marker, although not all LAMP1-labeled organelles are true degradative lysosomes [1]. Lamp1 is involved in the endolysosomal system, which is crucial for cellular catabolism, nutrient recycling, and signaling. It also participates in processes like autophagy and lipid transport, and its functions are related to maintaining cellular homeostasis [2].

In Drosophila, Lamp1 is dispensable for viability and autophagy, but it is involved in lipid metabolism as its deficiency leads to defects in lipid transport, with elevated levels of sterols and diacylglycerols [2]. In Drosophila models of Parkinson's disease, lack of Lamp1 increases susceptibility to paraquat (a pro-oxidant) and exacerbates locomotor defects induced by mutant α-synuclein, suggesting a role in protecting against oxidative stress and α-synuclein neurotoxicity [4]. In mice, while single deficiency in Lamp1 is viable, double deficiency of Lamp1 and Lamp2 is embryonic lethal, indicating shared functions, and Lamp2 single-deficiency has more severe consequences [3].

In conclusion, Lamp1 has diverse functions in cells, playing important roles in lipid transport, protection against oxidative stress and neurotoxicity in neurodegenerative disease models. Gene-knockout studies in Drosophila and mice have been valuable in revealing these functions, contributing to our understanding of biological processes and disease mechanisms related to the endolysosomal system.