The amino acid sequence of the D-ribose-binding protein from Escherichia coli K12 was determined from the DNA sequence of the gene. Protein sequence analyses covering 80% of the protein were consistent with the sequence deduced from the DNA. The mature binding protein has 271 amino acid residues and shows substantial homology to D-galactose-binding protein. A signal peptide sequence of 23 or 25 residues was also deduced from the DNA sequence. It shows the characteristic features of prokaryotic signal peptides.