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 (By similarity). 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). Acts also as a negative regulator of osteoclast activity (PubMed:31173907). May be involved in interleukin-4-induced M2 macrophage polarization (By similarity). Acts also as a negative regulator of osteoclast activity (PubMed:31173907). May be involved in interleukin-4-induced M2 macrophage polarization (By similarity). Knockout zebrafish are viable and fertile and display no obvious morphological defects as adults (PubMed:31173907, PubMed:31036939). However deficient zebrafish have abnormal microglial with expended lysosomes (PubMed:31036939). They also display increased bone resorption (PubMed:31173907). Belongs to the GPR137 family.