Mammalian and bacterial sugar transport proteins are homologous

• Published in: Nature (London) Vol. 325; no. 6105; pp. 641 - 643
• Main Authors: Maiden, Martin C. J, Davis, Elaine O, Baldwin, Stephen A, Moore, Duncan C. M, Henderson, Peter J. F
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 12-02-1987; Nature Publishing Group
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Arabinose - genetics; Arabinose - metabolism; Bacteria; Base Sequence; Binding and carrier proteins; Biochemistry; Biological and medical sciences; Carbohydrate Metabolism; Carrier Proteins - analysis; Carrier Proteins - genetics; Cloning; E coli; Escherichia coli; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Glucose - genetics; Glucose - metabolism; Humans; Lactose - genetics; Lactose - metabolism; Mammals; man; Medical research; Membranes; Proteins; rats; Sugar; Xylose - genetics; Xylose - metabolism; Human; Rat; Molecular structure; Escherichia coli; Rodentia; Brain (Vertebrata); Homology; Vertebrata; Mammalia; Liver cell carcinoma; Bacteria; Carbohydrate; Escherichieae; Carrier protein; Enterobacteriaceae
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/325641a0

The uptake of a sugar across the boundary membrane is a primary event in the nutrition of most cells, but the hydrophobic nature of the transport proteins involved makes them difficult to characterize. Their amino-acid sequences can, however, be determined by cloning and sequencing the corresponding gene (or complementary DNA). We have determined the sequences of the arabinose-H+ and xylose-H+ membrane transport proteins of Escherichia coli. They are homologous with each other and, unexpectedly, with the glucose transporters of human hepatoma and rat brain cells. All four proteins share similarities with the E. coli citrate transporter. Comparisons of their sequences and hydropathic profiles yield insights into their structure, functionally important residues and possible evolutionary relationships. There is little apparent homology with the lactose-H+ (LacY) or melibiose-Na+ (MelB) transport proteins of E. coli.