Probably helps membrane protein MSMEG_3069/MSMEI_2992 (P55) transport triacylglycerides (TAG) across the inner cell membrane into the periplasm and probably ultimately to the outer membrane (By similarity). Required for MSMEG_3069/MSMEI_2992 export activity. Export of ethidium bromide by MSMEG_3069/MSMEI_2992 can be complemented by the equivalent operon from M.tuberculosis (lprG-Rv1410c) (PubMed:18156250). Forms a U-shaped beta-half-barrel with a small hydrophobic cavity able to hold a triacylated lipid or triacylglyceride. Double deletions of lprG-MSMEG_3069/MSMEI_2992 operon are more sensitive to ethidium bromide; restoration of wild-type growth is conferred by the M.tuberculosis operon. Cells display abnormal colony morphology and are defective for sliding motility under cabon-limiting conditions (PubMed:18156250). Belongs to the LppX/LprAFG lipoprotein family.