The core Escherichia coli signal recognition particle receptor contains only the N and G domains of FtsY

Previous studies have proposed that the N-terminal A domain (similar to200 amino acid residues) of the Escherichia coli signal recognition particle (SRP) receptor, FtsY, is required for membrane targeting. In contrast to this suggestion, we show that A domain-truncated versions of FtsY, harboring only domains N and G, are functional. Therefore, we propose that N and G domains constitute the core SRP receptor.