Lysosomal integral membrane protein that regulates the localization and activity of mTORC1, a signaling complex promoting cell growth in response to growth factors, energy levels, and amino acids (PubMed:31036939). Interacts with Rag GTPases and increases the lysosomial localization and activity of Rag GTPases and thereby regulates mTORC1 translocation and activity in lysosome (PubMed:31036939). Involved in the regulation of lysosomal morphology and autophagy (PubMed:31036939). Acts also as a negative regulator of osteoclast activity (By similarity). Involved in interleukin-4-induced M2 macrophage polarization (By similarity). Interaction with RRAGA; increases RRAGA recruitment to lysosomes (PubMed:31036939). Interacts with MTOR; this interaction is amino acid sensitive (PubMed:31036939). Colocalized with MTOR in lysosome after amino acid stimulation. Expressed in kidney, heart, brain and placenta. Belongs to the GPR137 family.