Fig. 2.

Micrographs of negative-stained band B2, obtained by sucrose density gradient centrifugation. a Note the cup-shaped structure (white arrow) and the sheet-like structure (white arrowhead). b The monomeric/oligomeric particles are shown in higher magnifications. Some are marked with black arrowheads. The insert in micrograph b is further enlarged. For better display, the digitized pictures were adjusted for brightness and contrast. The scale bars are indicated