Might be involved in translocating phthiocerol dimycocerosates (PDIM) from the cell membrane to the outer membrane; PDIM forms part of the cell wall. Forms a U-shaped beta-half-barrel with a large hydrophobic cavity (2835 Angstroms(3)) which is large enough to hold a single phthiocerol dimycocerosate (PDIM) molecule. Modified by Lgt on Cys-27 with an S-linked diacylglycerol with a mixture of C16 and C19 fatty acids (palmitic and tuberculostearic acid), signal peptide is removed by LspA, modified by Lnt with an amide-linked mixture of C16 and C19 fatty acids, expressed in M.bovis and M.smegmatis (PubMed:19661058, PubMed:24093492). Hexose glycosylated in N-terminus between residues 27 and 55; there may be 2 sugar moieties in this region, expressed in M.bovis (PubMed:24093492). Expressed in M.bovis, lipidated and glycosylated. No growth phenotype when grown in culture, no release of phthiocerol dimycocerosates (PDIM) to the culture filtrate. Attenuated virulence, about 80-fold less recovery of bacteria from lungs of 3 week infected BALB/c mice. Belongs to the LppX/LprAFG lipoprotein family.