Transports trehalose monomycolate (TMM) to the cell wall (PubMed:31239378, PubMed:22520756, PubMed:28698380). Flips TMM across the inner membrane. Membrane potential is not required for this function (PubMed:28698380). Transports probably phosphatidylethanolamine (PE) as well. Binds specifically both TMM and PE, but not trehalose dimycolate (TDM). Binds also diacylglycerol (DAG) and other phospholipids, including phosphatidylglycerol (PG), phosphatidylinositol (PI), and cardiolipin (CDL) (PubMed:31113875). Contributes to membrane potential, cell wall composition, antibiotic susceptibility and fitness (PubMed:28703701). Inhibited by the antimycobacterial compound BM212, a pyrrole derivative (PubMed:28698380). Inhibited by the antitubercular drug SQ109. Inhibited by the adamantyl urea derivative AU1235, the indole carboxamide ICA38 and rimonabant, the antagonist for the cannabinoid receptor CB1. The dissociation constant (Kd) values for SQ109, AU1235, ICA38 and rimonabant are 1.65 uM, 0.29, 0.16 and 29.5, respectively (PubMed:30682372). Inhibitory effects are due to binding of the inhibitors at the proton-transportation channel most likely dissipating the transmembrane electrochemical proton gradient needed for substrate translocation (PubMed:30682372 PubMed:32512002). Monomer (PubMed:30682372, PubMed:31113875). Interacts with TtfA (via N-terminus); active trehalose monomycolate (TMM) biosynthesis is not required for the complex formation. Interacts with MSMEG_5308 (PubMed:31239378). Colocalizes with TtfA to the cell poles and septa. Trehalose monomycolate (TMM) synthesis is not required for localization to the poles or septa. Cells lacking this gene are not viable (PubMed:22520756). Knockdown or depletion of this gene leads to accummulation of trehalose monomycolate (TMM) and lack of trehalose dimycolate (TDM) (PubMed:31239378, PubMed:22520756). Decrease in mycolylation of arabinogalactan (AG) (PubMed:22520756). Accumulates MSMEG_5308 protein (PubMed:31239378). This protein is a target of small molecules which can be validated by developed assays that measure the topology of trehalose monomycolate (TMM) in the inner membrane of mycobacterial spheroplasts after which they may be developed to future antituberculosis drugs (PubMed:28698380). Designing improved inhibitors against this protein could be achieved by avoiding direct contacts with the identified residues that can mutate to confer drug resistance. Alternatively, incorporating conformational flexibility in the inhibitors can allow them to adapt to structural changes in the inhibitor binding pocket due to mutation (PubMed:30682372). Binds antitubercular compounds N-(4,4-dimethylcyclohexyl)-4,6-difluoro-1H-indole-2-carboxamide (NITD-349) and 1-((2,3-dihydrobenzo[b][1,4]dioxin-6-yl) methyl)-6',7'-dihydrospiro[piperidine-4,4'-thieno[3,2-c]pyran] (SPIRO) with Kd values of 0.05 uM and 0.8 uM, respectively. Belongs to the resistance-nodulation-cell division (RND) (TC 2.A.6) family. MmpL subfamily.