The first entity is a component of the second entity, which is a complex. This interaction is transient in the sense that A component_of B and B component_of C implies A component_of C. This interaction is directed.
The first entity controls a reaction that changes the state of the second entity, e.g. by phosphorylation or other posttranslational modification, or by a change in subcellular location. This interaction is directed.
The entities participate in a conversion as substrates or products. Controllers are not included. This interaction is undirected.
The entities participate in an interaction. Controllers are not included. This interaction is undirected.
The entities catalyze two conversions that are connected via a common molecule, e.g. the first entity produces a substrate that is consumed by the second entity. This interaction is directed.