An interaction is inferred when a bait protein is affinity captured from cell extracts by either polyclonal antibody or epitope tag and the associated interaction partner is identified by mass spectrometric methods.

An interaction is inferred from the biochemical effect of one protein upon another, for example, GTP-GDP exchange activity or phosphorylation of a substrate by a kinase. The bait protein executes the activity on the substrate hit protein. A Modification value is recorded for interactions of this type with the possible values Phosphorylation, Ubiquitination, Sumoylation, Dephosphorylation, Methylation, Prenylation, Acetylation, Deubiquitination, Proteolytic Processing, Glucosylation, Nedd(Rub1)ylation, Deacetylation, No Modification, Demethylation.

An interaction is inferred when a bait-enzyme fusion protein selectively modifies a vicinal protein with a diffusible reactive product, followed by affinity capture of the modified protein and identification by mass spectrometric methods.