Might be involved in transporting short diacylated glycolipids to the cell outer membrane. Binds glycolipids that contain a diacylated glycerophosphate or a diacylated phosphatidylinositol moiety with C14 and C16 chains (upon overexpression in M.smegmatis; M.smegmatis does not encode this gene). Overexpression in M.smegmatis increases the cell wall glycolipid LAM/LM ratio (lipoarabinomannan/lipomannan), suggesting perhaps this protein is involved in the preferential translocation of diacylated LAM to the outer cell membrane. Overexpressing M.smegmatis cells adhere less well to hexadecane droplets, indicating decrease in the hydrophobicity of the cell surface, and have a slightly increased resistance to the antibiotic ethambutol. Monomer. Forms a U-shaped beta-half-barrel with a small hydrophobic cavity (933 Angstroms(3)) which is large enough to hold a single diacylated glycolipid molecule. Modified by Lgt on Cys-39 with an S-linked diacylglycerol with a mixture of C16, C18 and C19 fatty acids (palmitic, stearic and tuberculostearic acid respectively), signal peptide is removed by LspA, modified by Lnt with an amide-linked mixture of C16 and C19 fatty acids (By similarity). Belongs to the LppX/LprAFG lipoprotein family.