Figure 4.

Electrostatic properties of K₄₈-linked tetra-ubiquitin in closed and open conformations. A. Conformation and properties of the closed form of tetra-ubiquitin rendered in surface representation. Hydrophobic patches of ubiquitin units are in contact with each other, and are not exposed to solvent. Shown in the middle and on the right are the electrostatic properties of two sides of the closed form. B. Example of an open conformation of K₄₈-linked tetra-ubiquitin. The structure shown is representative of the largest cluster of configurations obtained in a 200 ns simulation. The images in the middle column correspond to the conformations shown in the left column. The color scale of electrostatic potential is the same as in Fig. 3 (k_BT/e).