R bodies

[1] Encoded by a single operon containing four open reading frames,[3][4] R bodies are formed from two small structural proteins, RebA and RebB.

[5] At low pH, Type 51 R bodies undergo a dramatic structural rearrangement.

Much like a paper yo-yo, the ribbon extends (from the center) to form hollow tube with pointed ends that can reach up to 20μm in length.

[6] Other types of R bodies from different bacterial species vary in their size, ribbon morphology, and triggers for extension.

[7] While feeding kappa particles to sensitive paramecium results in the death of paramecium, feeding purified R bodies or R bodies recombinantly expressed in E. coli is not toxic.