Mechanosensation: Touch at the molecular level

Touch and the related sense of proprioception are the most ubiquitous, yet the least understood, of the senses. In vertebrates, the sensory terminals of touch receptors and proprioreceptors are far from the cell bodies, dispersed throughout the body and embedded in other tissues, impeding the electrophysiological recording of mechanoreceptor potentials and biochemical purification of components of the molecular machinery that mediates mechanosensation. An alternative approach to understanding mechanotransduction has been to isolate touch-insensitive mutants in genetically tractable organisms. This approach is beginning to bear fruit, as evidenced by the recent cloning of genes needed for gentle touch sensitivity in the nematode Caenorhabditis elegans, which seem to encode components of a mechanosensory ion channel complex.