Mediates uptake of riboflavin and roseoflavin, a toxic riboflavin analog; may also transport FMN. Probably a riboflavin-binding protein that interacts with the energy-coupling factor (ECF) ABC-transporter complex. Unlike classic ABC transporters this ECF transporter provides the energy necessary to transport a number of different substrates. The substrates themselves are bound by transmembrane, not extracytoplasmic soluble proteins (By similarity). Inhibited by excess of riboflavin or FMN. Also inhibited by protonophores such as CCCP and FCCP or in the absence of glucose. Forms a stable energy-coupling factor (ECF) transporter complex composed of a membrane-embedded substrate-binding protein (S component), 2 ATP-binding proteins (A component) and 2 transmembrane proteins (T component). May be able to interact with more than 1 S component at a time (By similarity). Induced by riboflavin deficiency. Abolishes riboflavin uptake, cell growth less inhibited by roseoflavin. Belongs to the prokaryotic riboflavin transporter (P-RFT) (TC 2.A.87) family.