Figure 2.

Concise representation of alternative binding modes. Example: heterodimers formed by Cyclins E, A, and B binding to Cdk1 or 2. (a) CycE:Cdk2; (b) Cdk2 complexed with either CycE or CycA; (c) CycA:Cdk2; (d) CycA complexed with either Cdk2 or Cdk1; (e) CycA:Cdk1; (f) Cdk1 complexed with either CycA or CycB. Note that a, c, d, e, and g each lie on a unique connector line, and each represents a unique heterodimer. Nodes b, d, and f, on the other hand, represent dimer combinations. This notation greatly simplifies the representation of multiple alternative interactions: for example, the interactions of p21, p27, or p57 with various Cyclin:Cdk dimers in Figure 6A. A formal rule, required to avoid ambiguity, is that lines representing alternative interactions must join at an acute angle.