Sequence of the lactose permease gene

The nucleotide sequence of the lacY gene coding for lactose permease (M protein) in Escherichia coli has been determined. The sequence includes the intergenic regions between the lacZ (β-galactosidase) and lacY genes as well as the region between the lacY and lacA (transacetylase) genes. Lactose permease is predicted to consist of 417 residues (71% nonpolar), resulting in a protein with a molecular weight of 46,504. The reading frame was confirmed by the sequence of a nonsense mutation changing codon 33 from UGG to UAG.