Probably a thiamine-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). Forms a stable energy-coupling factor (ECF) transporter complex composed of a membrane-embedded substrate-binding protein (S component), two ATP-binding proteins (A components) and a transmembrane protein (T component). Cells display deregulation of thiamine biosynthesis and impaired export of thiamine products from the cell. Belongs to the vitamin uptake transporter (VUT/ECF) (TC 2.A.88) family. Thiamine transporter subfamily.