(B) Mapping of the boundary of the FtsH generated proteolytic product of MgtE. Immunoblot comparing the SDS PAGE mobility of the N-terminal fragment of endogenous MgtE generated by FtsH in the presence of the pseudoprotease version of YqgP (catalytically dead YqgP.S288A, strains BTM78, BTM502, Table EV2) to the mobilities of in vitro translated reference fragments corresponding to MgtE 1-340, -355 and -370 shows that YqgP.S288A acts as an FtsH adaptor, and that FtsH processing of MgtE in the presence of YqgP.S288A stops at around amino acid 355, which is near or at the cytoplasmic end of TMH 3 of MgtE. 