Figure 5.
Myosin Iβ immunoreactivity in bullfrog hair cells. (A and B) Immunofluorescence of single dissociated cells shows myosin Iβ in the cell body and also in the hair bundle where it is especially concentrated at the tips of stereocilia. The kinocilium also shows fluorescent label. (Scale bar = 2 μm.) (C) Transmission electron micrograph (×30,000) showing a longitudinal section of two adjacent stereocilia. The arrow indicates the tip-link insertion and the electron-dense plaque, the presumed site of the adaptation motors. (D) Immunogold electron microscopy localizing myosin Iβ at both ends of tip links. (Scale bar = 500 nm.) (E) Summary of myosin Iβ distribution in the tips of stereocilia. Gold particles marking the antibody were counted and averaged over many stereocilia in six bundles, and their density is indicated as particles/μm2 of surface membrane. The greatest density is within ≈200 nm of either end of the tip link. [Reprinted with permission from ref. 44 (Copyright 1998, Society for Neuroscience).]