Part of the tripartite ATP-independent periplasmic (TRAP) transport system UehABC, which imports both ectoine and 5-hydroxyectoine as nutrients, and not as osmoprotectants. UehA binds both ectoine and 5-hydroxyectoine with high specificity and affinity. Monomer (PubMed:19362561). The complex comprises the extracytoplasmic solute receptor protein UehA, and the two transmembrane proteins UehB and UehC (Probable). Transport is enhanced in cells that are grown in the presence of ectoine, but not by high-salinity media. Belongs to the bacterial solute-binding protein 7 family.