Localization of proteins associated with the outer hair cell plasma membrane in the gerbil cochlea

There is substantial evidence that the motility of mammalian outer hair cells is generated close to or within the plasma membrane. Several analogies between the outer hair cell cortical lattice and the membrane-related cytoskeleton of erythrocytes have been noted. In erythrocytes a member of the anion exchanger protein family, AE1, also known as Band 3, is involved in membrane-cytoskeleton linkage via Protein 4.1. In the following paper, the presence of these two proteins in gerbilline outer hair cells is confirmed by western blot. Furthermore, co-localization of these two proteins was detected in the lateral wall of outer hair cells by immunofluorescence and postembedding electron immunohistochemistry. Band 3 is restricted to this region, whereas Protein 4.1 has a somewhat more dispersed distribution. Thus, the structure of these sensory receptor cells may result from an adaptation of a strategy used by other motile cells. The proteins investigated likely have a support function and may comprise "pillars" seen between the lateral plasma membrane and the cytoskeleton in micrographs of outer hair cells. The possibility that Band 3 comprises "protein particles" seen in the lateral plasma membrane, or maybe directly involved in the voltage-dependent force generation in outer hair cells, is also discussed.