Influence of the presence of the signal sequence on YedY expression in R. sphaeroides . (A) An image of the membrane after western blot analysis. Whole cell extracts or soluble extracts (25 μg) were loaded on SDS PAGE. Lane -SS: cells harboring the pSM181 plasmid (which contains only the sequence encoding the mature protein). Lane + SS: cells harboring the plasmid pSM196 (which contains the signal sequence upstream of the sequence encoding the mature protein). (B) Western blot analysis of the soluble extracts -SS and + SS after different levels of dilution (for example 1/100 represents 100-fold less protein loaded and corresponds to 0.25 μg of protein). Western blot analysis was performed with anti-histidine peroxidase conjugate antibodies.