FIG. 4.

Substrate specificity of L. lactis MG1363 BcaP as determined by the inhibition of l-[¹⁴C]isoleucine uptake by l-amino acids. Shown is the percentage of l-[¹⁴C]isoleucine uptake by lactococcal cells overproducing BcaP in the presence of 250 μM unlabeled l-isoleucine (control) and a 10-fold excess of each of the 20 l-amino acids. The uptake was determined after 1 min of incubation at 30°C, and the assay was performed as described in the legend to Fig. 3. The means of three independent measurements are shown.