comment "Definition: An interaction in which participants bind physically to each other, directly or indirectly through intermediary molecules.
Rationale: There is a large body of interaction data, mostly produced by high throughput systems, that does not satisfy the level of detail required to model them with ComplexAssembly class. Specifically, what is lacking is the stoichiometric information and completeness (closed-world) of participants required to model them as chemical processes. Nevertheless interaction data is extremely useful and can be captured in BioPAX using this class.
Usage: This class should be used by default for representing molecular interactions such as those defined by PSI-MI level 2.5. The participants in a molecular interaction should be listed in the PARTICIPANT slot. Note that this is one of the few cases in which the PARTICPANT slot should be directly populated with instances (see comments on the PARTICPANTS property in the interaction class description). If all participants are known with exact stoichiometry, ComplexAssembly class should be used instead.
Example: Two proteins observed to interact in a yeast-two-hybrid experiment where there is not enough experimental evidence to suggest that the proteins are forming a complex by themselves without any indirect involvement of other proteins. This is the case for most large-scale yeast two-hybrid screens." (string)