LAMTOR1 is a family of eukaryotic proteins that have otherwise been referred to as Lipid raft adaptor protein p18, Late endosomal/lysosomal adaptor and MAPK and MTOR activator 1, and Protein associated with DRMs and endosomes.LAMTOR1 regulates the mTOR (mammalian target of rapamycin) pathway, a signaling cascade that promotes cell growth in response to growth factors, energy levels, and amino acids. LAMTOR1 is part of the Ragulator complex, recruits the Rag GTPases and the mTORC1 complex to lysosomes, a key step in activation of the TOR signaling cascade by amino acids []. LAMTOR1 is responsible for anchoring the Ragulator complex to membranes. It may regulate both the recycling of receptors through endosomes and the MAPK signaling pathway through recruitment of some of its components to late endosomes []. It may be involved in cholesterol homeostasis regulating LDL uptake and cholesterol release from late endosomes/lysosomes. It may also play a role in RHOA activation [, ].This family also includes Saccharomyces cerevisiae MEH1 (Ego1), a component of the EGO complex. The EGO complex and the Rag-Ragulator complex are structurally related []. The yeast EGO complex consists of Gtr1, Gtr2, Ego1, and Ego3, localises to the endosomal and vacuolar membranes, and plays a crucial role in cell growth and autophagy regulation through amino acid signals that activate TORC1 []. MEH1 (GSE2) is also a component of the GSE complex, which is required for proper sorting of amino acid permease Gap1 [].
