Figure 2

Illustrative renderings of proteins. Real-time halftoning and edge-line generation algorithms have been applied to ribbon and tube style displays generated from PDB structure files. (A) The porin protein [PDB:3POR], a transmembrane β-barrel structure [28, 29]. (B) The ribonuclease inhibitor protein [PDB:2BNH], a α/β horseshoe-shaped structure [30]. (C) The 3-isopropylmalate dehydrogenase enzyme [PDB:1A05], a three-layer (α-β-α) sandwich-structure [31], with two substrate molecules (C, gray; O, red; Mg²⁺, green). (D) The potassium channel [PDB:1BL8], a transmembrane α-domain structure [32], with a K+ ion (deep pink) in the channel. In all four images, loop regions are de-emphasized by showing them as thin ribbons with 75% translucency. In (A) to (C), α-helices are shown as tubes, while β-strands are shown as wide ribbons. In (D), the α-helices are shown as wide ribbons.