# Signal Transduction

Signal transduction is a fundamental biological process that occurs primarily on the surface of cells as a reaction to the sensed context of biochemical stimuli. Conversion, or transduction, of proteins at the surface into different proteins directly proceeds from whatever protein complexes, enzymes or hormonal signals are present. Each transduction gives rise to a new signal representing a new possible signaling pathway. Slight shifts in content and concentration of biochemical participants can lead to a rich number different signaling pathways.

Modeling of signal transduction must incorporate the molecular component level of detail, along with states of each of the involved components, to realistically capture the multitude of protein interactions that can occur. Computationally this gives rise to a large, complex system in which the number of chemical species in a system depends exponentially on the number of interactions in the system. This can grow to be quite large, even when few interactions are involved. BioNetGen strives to capture every possible resulting interaction that can spontaneously occur during signal transduction.