Figure 2.

Effect of progressive deletion of the central cytoplasmic loop. (A) Time course of lactose transport by E. coli T184 expressing the given mutants. (B) Permease expression. Membranes were prepared as described in the text, and 100 μg of protein was subjected to NaDodSO₄/PAGE and electroblotting. The blot was incubated with an anti-His₅ antibody, followed by horseradish peroxidase-linked protein A and luminescent substrate before exposure to film. WT, wild type; Δ5, deletion of residues 206–210; Δ12, deletion of residues 199–210; Δ20, deletion of residues 195–214; pT7–5, plasmid pT7–5 with no lacY insert.