Part of the tripartite ATP-independent periplasmic (TRAP) transport system involved in the uptake of monocarboxylate 2-oxoacids. This protein specifically binds monocarboxylate 2-oxoacids including pyruvate, 2-oxobutyrate, 2-oxovalerate, 2-oxoisovalerate, 2-oxoisocaproate and 2-oxo-3-methylvalerate. Is not able to bind mannitol. Pyruvate uptake inhibited by 2-oxobutyrate, 2-oxovalerate, 2-oxoisovalerate, 2-oxoisocaproate and 2-oxo-3-methylvalerate. Homodimer. The complex comprises the extracytoplasmic solute receptor protein all3028, and the two putative transmembrane proteins alr3026 and alr3027 (By similarity). Impaired pyruvate uptake. Belongs to the bacterial solute-binding protein 7 family.