FIGURE 2. The 
-folium fold.
From the following article:
Structure of the bacterial flagellar protofilament and implications for a switch for supercoiling
Fadel A. Samatey, Katsumi Imada, Shigehiro Nagashima, Ferenc Vonderviszt, Takashi Kumasaka, Masaki Yamamoto and Keiichi Namba
Nature 410, 331-337(15 March 2001)
doi:10.1038/35066504
Left, residues 220–260 in domain D3; middle, residues 308–345 in domain D2a; right, residues 345–383 in domain D2b. The chain is colour coded from blue to green to brown according to the amino-acid sequence. Prepared with MOLSCRIPT44 and RASTER3D45.
