Required for the transport across the inner membrane of sulfolipid-1 (SL-1), which is a major cell wall lipid of pathogenic mycobacteria. Could also transport SL1278 (2-palmitoyl-3-(C43)-phthioceranyl-alpha, alpha'-D-trehalose-2'-sulfate), which is the precursor of SL-1. May potentiate SL-1 levels and confer specificity for sulfolipids over structurally similar glycolipids. Accumulates the precursor SL1278. Can produce SL-1, albeit at reduced levels. Belongs to the peptidoglycolipid addressing protein (GAP) (TC 2.A.116) family.