Lysosomes are membrane-bound organelles responsible for the degradation of various biological macromolecules. Vesicles containing hydrolytic enzymes bud from the Golgi and fuse with endosomes to form the mature lysosome capable of breaking down various types of cargo. Their general function in recycling biological molecules places lysosomes at center of various processes including autophagy, endyocytosis, and phagocytosis. These functions are essential for maintaining cellular homeostasis through, for example, autophagy of damaged organelles or the endocytosis and degradation of activated signaling receptor complexes. Lysosomal-associated membrane protein-2 (LAMP-2) is ubiquitously expressed and is an abundant component of the lysosomal membrane. LAMP-2 contains a large luminal domain that is heavily glycosylated followed by a single transmembrane domain and a small cytoplasmic facing carboxyl terminus. LAMP-2 acts as a receptor for the degradation of specific cytosolic cargo during chaperone-mediated autophagy and also regulates fusion of the lysosome with the autophagosome. Mutation of LAMP-2 leads to the accumulation of autophagosomes and causes Danon disease, a disorder characterized by skeletal and cardiomyopathy as well as mental retardation.
Given the abundance of LAMP-2 and its specific localization, LAMP-2 antibodies are excellent markers for late endosomes and lysosomes. The Kopito group at Stanford used the LAMP-2 antibody to localize lysosomes during their investigation of microtubules in the autophagic degradation of Huntingtin protein (1). In addition to its use as a lysosome marker, the monoclonal LAMP-2 antibody was used in a study to show elevated expression in pancreatic cancer cells (2). This study demonstrates potential for LAMP-2 as a prognostic indicator in pancreatic carcinoma. Zhang et al. studied the mechanisms of entry into host cells by Salmonella (3). Salmonella bacteria escape from Salmonella-containing vacuoles (SCV) into the cytoplasm. Using LAMP-2 antibody as a marker for mature SCVs, the researchers identified an effector protein that is necessary for bacterial escape into the cytoplasm. A study by Bandari et al. used the LAMP-2 antibody to follow the endocytosis and trafficking of the chemokine receptor CXCR4 (4). In arrestin-2 depleted cells CXCR4 accumulates in early endosomes but does not traffic to lysosomes. This study identified arrestin-2 as a component that regulates the sorting and degradation of CXCR4.
Novus Biologicals offers LAMP-2 reagents for your research needs including:
PMIDs
