Figure 5.

Lactococcal N-terminal signal peptides fused to the yeast ADP/ATP carrier AAC1. (A) Schematic representation of the lactococcal signal peptides from OppA, PrtP, and Usp45 fused to the N terminus of AAC1. The cleavage sites of the endogenous signal peptidases as indicated by a pair of scissors were predicted with SignalP (Bendtsen et al. 2004). Western blot (B) and transport activity (C) of the fusion proteins in comparison to the wild-type AAC1. The black arrow indicates the molecular weight of the full-length signal peptide-AAC1 fusion, and the white arrow, the mature protein after the signal peptide has been removed by endogenous signal peptidases. The initial uptake rates, measured after 1 min, are the average of three independent experiments carried out in triplicate with the standard error of the mean (SEM).