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 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.

Interaction directly demonstrated at the atomic level by X-ray crystallography. Also used for NMR or Electron Microscopy (EM) structures. If there is no obvious bait-hit directionality to the interaction involving 3 or more proteins, then the co-crystallized proteins should be listed as a complex.

A genetic interaction is inferred when mutation or over expression of one gene results in suppression of any phenotype (other than lethality/growth defect) associated with mutation or over expression of another gene.

An interaction is inferred between proteins in vitro. This can include proteins in recombinant form or proteins isolated directly from cells with recombinant or purified bait. For example, GST pull-down assays where a GST-tagged protein is first isolated and then used to fish interactors from cell lysates are considered reconstituted complexes (e.g. PUBMED: 14657240, Fig. 4A or PUBMED: 14761940, Fig. 5). This can also include gel-shifts, surface plasmon resonance, isothermal titration calorimetry (ITC) and bio-layer interferometry (BLI) experiments. The bait-hit directionality may not be clear for 2 interacting proteins. In these cases the directionality is up to the discretion of the curator.

A genetic interaction is inferred when mutations or deletions in separate genes, each of which alone causes a minimal phenotype, result in lethality when combined in the same cell under a given condition.