In the accompanying paper [Adams, H., Scotti, ., de Cock, H., Luirink, J. & Tommassen, J. (2002)Eur. J. , 5564–5571.], we showed that the precursor of outer-membrane proteinPhoEofEscherichia coliwithaGly to Leu substitution at position )10 in the signal sequence (G-10L) is targeted to the SecYEGtranslocon via the signal-recognition particle (SRP) route, instead of via the SecB pathway. Here, we studied the fate of the mutant precursor in aprlA4mutant strain.