This graph provides an qualitative and quantitative overview of the different types of signaling domains and signaling machinery (e.g. response regulators, etc) present in a bacterium. It is important to note that this graph is based on domain counts, rather than protein counts. Thus, because of multi-domain propteins as well as specific classification rules, these amounts will not necessarily equal the number of proteins containing a given domain(s). For example, the graph may show 60 receiver domains for an organism that only contains 55 response regulator proteins. This discrepancy is due to such things as hybrid histidine kinases (HHK) which contain transmitter and receiver domains. Consequently, this protein would contribute to both the transmitter and receiver counts on the graph. The bars on the graph are hyperlinked and when clicked display those proteins that contain the corresponding signaling domain.
Based on their role in signal transduction, all signaling domains are assigned a a specific "kind" and further subdivided into various functional categories. These aid in the classification process and the amount present in a bacterium is graphically portrayed with a bar chart. An example and legend definition is given below.