Editing Secretion (section)

===Type III secretion system (T3SS or TTSS)===
{{Main|Type III secretion system}}
[[Image:T3SS.svg|200px|right]]
It is homologous to the basal body in bacterial flagella. It is like a molecular syringe through which a bacterium (e.g. certain types of ''[[Salmonella]]'', ''[[Shigella]]'', ''[[Yersinia]]'', ''[[Vibrio]]'') can inject proteins into eukaryotic cells. The low Ca<sup>2+</sup> concentration in the cytosol opens the gate that regulates T3SS. One such mechanism to detect low calcium concentration has been illustrated by the lcrV (Low Calcium Response) antigen utilized by ''[[Yersinia pestis]]'', which is used to detect low calcium concentrations and elicits T3SS attachment. The Hrp system in plant pathogens inject harpins and pathogen effector proteins through similar mechanisms into plants. This secretion system was first discovered in ''[[Yersinia pestis]]'' and showed that toxins could be injected directly from the bacterial cytoplasm into the cytoplasm of its host's cells rather than simply be secreted into the extracellular medium.<ref>Salyers, A. A. & Whitt, D. D. (2002). ''Bacterial Pathogenesis: A Molecular Approach'', 2nd ed., Washington, D.C.: ASM Press. {{ISBN|1-55581-171-X}}{{page needed|date=February 2013}}</ref>