LAMP1
Description
The LAMP1 (lysosomal associated membrane protein 1) is a protein-coding gene located on chromosome 13.
Lysosomal-associated membrane protein 1 (LAMP-1), also known as lysosome-associated membrane glycoprotein 1 and CD107a (Cluster of Differentiation 107a), is a protein that in humans is encoded by the LAMP1 gene. The human LAMP1 gene is located on the long arm (q) of chromosome 13 at region 3, band 4 (13q34). Lysosomal-associated membrane protein 1 is a glycoprotein from a family of Lysosome-associated membrane glycoproteins. The LAMP-1 glycoprotein is a type I transmembrane protein which is expressed at high or medium levels in at least 76 different normal tissue cell types. It resides primarily across lysosomal membranes, and functions to provide selectins with carbohydrate ligands. CD107a has also been shown to be a marker of degranulation on lymphocytes such as CD8+ and NK cells, and may also play a role in tumor cell differentiation and metastasis. Residing primarily across lysosomal membranes, these glycoproteins consist of a large, highly glycosylated end with N-linked carbon chains on the luminal side of the membrane, and a short C-terminal tail exposed to the cytoplasm. The extracytoplasmic region contains a hinge-like structure which can form disulphide bridges homologous to those observed in human immunoglobulin A. Other characteristics of the structure of the LAMP-1 glycoproteins include: A polypeptide core of ~40kDa 18 {N-glycosylation} sites to help with the addition of sugar chains Polylactosamine attachments which protect the glyocoprotein from degradation by lysosomal proteases Significant quantities of polylactosaminoglycan and sialic acid to traverse the trans-Golgi cisternae. poly-N-acetyllactosamine groups which are involved in interactions with selectin and other glycan-binding proteins LAMP1 and LAMP2 glycoproteins comprise 50% of all lysosomal membrane proteins, and are thought to be responsible in part for maintaining lysosomal integrity, pH and catabolism. The expression of LAMP1 and LAMP2 glycoproteins are linked, as deficiencies in LAMP1 gene will lead to increased expression of LAMP2 glycoproteins.
LAMP1 is a lysosomal membrane glycoprotein that plays a crucial role in lysosome biogenesis, lysosomal pH regulation, autophagy and cholesterol homeostasis. It acts as a direct inhibitor of the proton channel TMEM175, facilitating lysosomal acidification for optimal hydrolase activity. LAMP1 also plays an important role in NK-cell cytotoxicity by participating in cytotoxic granule movement to the cell surface and perforin trafficking to the lytic granule. It also protects NK-cells from degranulation-associated damage. LAMP1 presents carbohydrate ligands to selectins.
LAMP1 is also known as CD107a, LAMPA, LGP120.
