Required for Yop secretion. Interacts with YscY. Secreted via the type III secretion system. Temperature seems to play the major role in regulation of transcription of the lcrE-containing operon of pYV, whereas Ca(2+) concentration has only a moderate effect at 37 degrees Celsius, and no effect at room temperature. The region between residues 50 and 110, which contains the predicted coiled coil domain, is essential for interaction with YscY. May possess both an mRNA signal and a syc-dependent signal capable of directing its export through the type III secretion system.