SUMMARY: Glucosamine, mannose and 2-deoxyglucose enter Escherichia coli by the phosphotransferase system coded for by the gene ptsM. The glucosamine- and mannose-negative, deoxyglucose-resistant phenotype of ptsM mutants can be suppressed by a mutation mapping near ptsG that allows constitutive expression of the glucose phosphotransferase coded for by the gene ptsG.