Figure 1.

Helical structure of the tip link. (A) Proposed model for tip-link structure. Two helically intertwined protofilaments (Inset) make up the tip link, attaching at two points to the taller stereocilium and contacting three filaments emanating from the shorter stereocilium. (B) Freeze-etch image of tip link from guinea pig cochlea. Note the thick carbon coat forming a halo around the tip link and the stereocilia surface. (C) Higher magnification view of the tip link in B; we suggest that the reader view this figure from a shallow angle perspective (from bottom to top) to better view the helical configuration of the tip link. We confirmed right-handedness by imaging stereo pairs with the concave side of the replica up. (D) Surface plot of the pixel intensities of the digitized image of the tip link shown in B created with National Institutes of Health image. The pseudo-three-dimensional image helped visualize the helical configuration and the possible periodic substructure of the protofilaments. (Scale bars: B = 50 nm; C and D = 10 nm.)