Type III secretion systems (TTSS) are virulence associated components of many Gram-negative bacteria that translocate bacterial proteins directly from the bacterial cytoplasm in to the host cell cytoplasm. Existing data on the translocated Yop proteins of Yersinia suggest the existence of two independent signals present in the amino terminus of the protein that direct secretion and translocation respectively. In Yersinia TTSS secretion is facilitated by the N-terminal mRNA sequence corresponding to the first 15 codons, while translocation is dependent on the region between amino acids 50 and 100. The Salmonella effector protein SopE has no consensus cleavable N-terminal sequence or any documented secretion signal. A chaperone, encoded by invB, is involved in the secretion/translocation of SopE1 by an unknown signal/mechanism. Previous studies have demonstrated that the N-terminal sequence of the protein is enough for secretion but the significance of the 5 mRNA sequence has not yet been determined. We have investigated the N-terminal region of SopE1 in S. typhimurium SL3261 confirming the importance of the amino acid sequence for secretion. Frameshift mutation analysis involving all or part of the N-terminal SopE sequence, has improved our insight on the conserved regions of the protein important for TTSS-dependent secretion. The significance of the 5 mRNA sequence was investigated in an attempt to identify novel consensus signal sequences implicated in translocation of SopE-like effector proteins into mammalian cells.