Soluble FtsY- signal recognition particle (SRP) - MtlA189 ribosome-nascent chains (RNCs) are not efficiently targeted to inner membrane vesicles. (A) In vitro synthesized MtlA189 RNCs were incubated with purified SRP, FtsY or both in the presence of guanosine 5'(β,-γ imido) triphosphate (GMP)-PNP. The RNCs were subsequently isolated by centrifugation through a sucrose cushion and resuspended in buffer (50 mM triethanolamine acetate, pH 8; 50 mM potassium acetate; 5 mM magnesium acetate; 1 mM DTT). One volume was directly trichloroacetic acid precipitated and five volumes were subjected to immune precipitation using sepharose-bound polyclonal antibodies against either Ffh or FtsY. As control pre-immune serum (Pre-IS) was used. (B) The MtlA189 RNCs shown in A, and containing either SRP or SRP and FtsY, were incubated with the indicated inner membrane vesicles (1 μl, 50 μg protein) and subjected to flotation gradient centrifugation.
Mircheva et al. BMC Biology 2009 7:76 doi:10.1186/1741-7007-7-76