Interactome research has shown that proteins participate in a wide number and variety of interactions.Together,these form networks of great complexity.However,the dynamics of these interactions remain unknown.We have defined three effects that control the dynamics of the interactome:quanttafive interaction effects,qualitative interaction effects and conditional interaction effects.The latter is concerned with interactions between proteins that are conditional on the presence of particular post-translational modifications.To understand the degree to which conditional interaction effects are important in the interactome,we first studied 8,378 incidences of 44 types of post-translational modifications to determine which are surface associated and which are not.