Figure 2. HK97 fold gallery.
Nine examples of the HK97 fold determined by X-ray crystallography or cryo-electron microscopy with secondary structure colored from N- to C-termini in blue to red hues. Protruding G-loops are colored orange, I-domains (Insertion domains) are colored magenta. Panels, in order: a, phage HK97 mature capsid protein [43]; b, Thermotoga maritima encapsulin [6]; c, Pyrococcus furiosus encapsulin (previously “PFV” for Pyrococcus fuiosus virus-like particle [39]); d, phage T4 mature major capsid protein gp23* [49]; e, P22 coat protein [19]; f, epsilon 15 mature capsid protein [50]; g, 80alpha procapsid major capsid protein [42]; h, phage TW1 major capsid protein [18]; i, phage T7 major capsid protein from the procapsid [41].