Schematic illustrations of the attachment organelle.

(A) Upper: Positions of internal proteins along attachment organelle determined from EYFP fluorescence. The average position in individual cells and SD relative to the cell edge are plotted with a black diamond and a colored bar, respectively. The proteins are mapped onto three localization groups, the terminal button (pink), the paired plates (green), and the bowl complex (blue). Middle: Distance between two signals measured from fluorescence microscopy. The positions of the terminal button, paired plates, and bowl complex are colored magenta, green, and cyan, respectively. Lower: Positions of internal proteins along a core determined from immunogold EM. The calculated peak and SD are presented as a black diamond and a bar, respectively. (B) Relations among four types of core structures. The slim, the fork, and the branched types are aligned to the EM grid in the common way. A possible reproduction cycle of an internal core is suggested by the arrow. (C) The attachment organelle including component proteins. The force is generated at the bowl complexes, is transmitted through the paired plates as indicated by a white arrow, and reaches the P1 adhesin complex.