Tip link

Tip links are extracellular filaments that connect stereocilia to each other or to the kinocilium in the hair cells of the inner ear.[1][2] Mechanotransduction is thought to occur at the site of the tip links, which connect to spring-gated ion channels.[3] These channels are cation-selective transduction channels that allow potassium and calcium ions to enter the hair cell from the endolymph that bathes its apical end. When the hair cells are deflected toward the kinocilium, depolarization occurs; when deflection is away from the kinocilium, hyperpolarization occurs. The tip link is made of two different cadherin molecules, protocadherin 15 and cadherin 23.[4] It has been found that the tip links are relatively stiff, so it is thought that there has to be something else in the hair cells that is stretchy which allows the stereocilia to move back and forth.[5]

Pictures G-N show the tip links connecting the stereocilia.

It is hypothesized that the tip link is attached to the myosin motor which moves along actin filaments.[6]

See also
  • Neuronal encoding of sound

References
  1. Pickles JO, Comis SD, Osborne MP. 1984.Cross-links between stereocilia in the guinea pig organ of Corti, and their possible relation to sensory transduction. Hearing Research 15:103-112.
  2. Scott T. Brady; George J. Siegel; Robert Wayne Albers; Donald Lowell Price (2012). Basic Neurochemistry: Principles of Molecular, Cellular and Medical Neurobiology. Academic Press. p. 920. ISBN 978-0-12-374947-5.
  3. David J. Aidley (3 September 1998). The Physiology of Excitable Cells. Cambridge University Press. pp. 248–. ISBN 978-0-521-57421-1.
  4. Lewin GR, Moshourab R. 2004. Mechanosensation and pain. Journal of Neurobiology 61:30-44
  5. Corey, D. Harvard University. Phone Interview. 19 November 2008.
  6. Howard, J.; Hudspeth, A. J. (1987). "Mechanical relaxation of the hair bundle mediates adaptation in mechanoelectrical transduction by the bullfrog's saccular hair cell". Proceedings of the National Academy of Sciences of the United States of America. 84 (9): 3064–3068. doi:10.1073/pnas.84.9.3064. PMC 304803. PMID 3495007.
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