LAPTM4B
Description
The LAPTM4B (lysosomal protein transmembrane 4 beta) is a protein-coding gene located on chromosome 8.
LAPTM4B is a protein that plays a role in lysosomal function and is involved in several cellular processes. It localizes to late endosomes and lysosomes and is overexpressed in various cancers. Elevated LAPTM4B levels are associated with chemotherapy resistance in breast cancer. It promotes autophagy, a cell survival mechanism, and contributes to tumor growth. LAPTM4B interacts with EGFR and regulates its activity, impacting cell signaling and survival.
LAPTM4B is essential for optimal lysosomal function. It prevents the breakdown of EGFR, a key growth factor receptor, by blocking its transport to lysosomes. LAPTM4B also interacts with PIP5K1C, an enzyme that produces phosphatidylinositol 4,5-bisphosphate, to inhibit the ubiquitination of HGS, another protein involved in EGFR degradation. Additionally, LAPTM4B recruits SLC3A2 and SLC7A5, a leucine transporter, to the lysosome, promoting leucine uptake and activating mTORC1, a key regulator of cell growth. It also plays a role in regulating the production of TGF-beta1, a signaling molecule, in immune cells. Finally, LAPTM4B binds to ceramide, a lipid involved in cell death, and facilitates its release from late endosomes, influencing cell survival pathways.
LAPTM4B is also known as LAPTM4beta, LC27.
