Part of the ABC transporter complex MetNPQ involved in methionine import. Binds the methionine and transfers it to the membrane-bound permease. It has also been shown to be involved in methionine sulfoxide transport (Probable). The complex is composed of two ATP-binding proteins (MetN), two transmembrane proteins (MetP) and a solute-binding protein (metQ). Repressed by methionine via the S-box system. Belongs to the NlpA lipoprotein family.