Regulator of the TOR pathway, a signaling cascade that promotes cell growth in response to growth factors, energy levels, and amino acids. As part of the Ragulator complex, may activate the TOR signaling cascade in response to amino acids. May play a role in late endosomes/lysosomes biogenesis and regulate both the recycling of receptors through endosomes and the MAPK signaling pathway. May be involved in cholesterol homeostasis. May also play a role in RHOA activation (By similarity). Involved in the control of embryonic stem cells differentiation; together with FLCN it is necessary to recruit and activate RRAGC/RagC and RRAGD/RagD at the lysosomes, and to induce exit of embryonic stem cells from pluripotency via non-canonical, mTOR-independent TFE3 inactivation (By similarity). Part of the Ragulator complex composed of lamtor1, lamtor2, lamtor3, lamtor4 and lamtor5. The Ragulator complex interacts with slc38a9; the probable amino acid sensor. Component of the lysosomal folliculin complex (LFC). Belongs to the LAMTOR1 family.