The following proteins involved in the uptake of phosphorylated metabolites, are evolutionary related [1,2]:

• Escherichia coli, Bacillus subtilis and Haemophilus influenzae glycerol-3- phosphate transporter (gene glpT).
• Salmonella typhimurium phosphoglycerate transporter (gene pgtP).
• Escherichia coli and Salmonella typhimurium hexose-6-phosphate transporter (gene uhpT).
• Escherichia coli and Salmonella typhimurium protein uhpC. UhpC is necessary for the expression of uhpT and seems to act jointly with the uhpB sensor/ kinase protein.
• Human glucose 6-phosphate translocase [3].

These proteins of about 50 Kd apparently contain 12 transmembrane regions. As a signature pattern we selected a conserved region in their central section.