Probably helps membrane protein ML0556 (P55) transport triacylglycerides (TAG) across the inner cell membrane into the periplasm and probably ultimately to the outer membrane. TAG probably regulates lipid metabolism and growth regulation. Binds di- and triacylated phosphatidyl-myo-inositol mannosides (PIMs), and glycolipid lipoglycan modulins lipoarabinomannan (LAM) and lipomannan (LM), facilitating their recognition by TLR2. Required for activity of drug efflux transporter ML0556. Required, probably with ML0556, for normal surface localization of LAM. Constitutes a host TLR2 agonist (toll-like receptor) able to stimulate proliferation of CD4+ T-cells derived from a human leprosy patient following protein processing/presentation by MHC class II molecules in peripheral blood mononuclear cells. Forms a U-shaped beta-half-barrel with a small hydrophobic cavity able to hold a triacylated lipid or triacylglyceride. Modified by Lgt on Cys-27 with an S-linked diacylglyceral, signal peptide is removed by LspA, Cys-27 is further modifed with a fatty acid on its amino group by Lnt yielding a triacylated protein (By similarity). Probably glycosylated, which is required for T-cell activation (PubMed:18424702). Bacterial LAM blocks host cell phagosome-lysosome fusion and is one way in which Mycobacteria evade the host immune system. Triacylglycerides accumulate in lipid droplets in the cytoplasm of M.leprae, and are used as an energy source during starvation. Belongs to the LppX/LprAFG lipoprotein family.