![The Tailchaser mutation does not affect formation of interstereocilial links](https://upload.wikimedia.org/wikipedia/commons/1/16/The_Tailchaser_mutation_does_not_affect_formation_of_interstereocilial_links.png)
Tip links are extracellular filaments that connect
stereocilia
Stereocilia (or stereovilli or villi) are non-motile apical cell modifications. They are distinct from cilia and microvilli, but are closely related to microvilli. They form single "finger-like" projections that may be branched, with normal cell ...
to each other or to the
kinocilium
A kinocilium is a special type of cilium on the apex of hair cells located in the sensory epithelium of the vertebrate inner ear.
Anatomy in humans
Kinocilia are found on the apical surface of hair cells and are involved in both the morphogenesis ...
in the hair cells of the
inner ear.
[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.] Mechanotransduction
In cellular biology, mechanotransduction ('' mechano'' + '' transduction'') is any of various mechanisms by which cells convert mechanical stimulus into electrochemical activity. This form of sensory transduction is responsible for a number of ...
is thought to occur at the site of the tip links, which connect to spring-gated ion channels.
These channels are cation-selective transduction channels that allow potassium and calcium ions to enter the hair cell from the
endolymph
Endolymph is the fluid contained in the membranous labyrinth of the inner ear. The major cation in endolymph is potassium, with the values of sodium and potassium concentration in the endolymph being 0.91 mM and 154 mM, respectively. I ...
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.
[Lewin GR, Moshourab R. 2004. Mechanosensation and pain. Journal of Neurobiology 61:30-44] 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.
[Corey, D. Harvard University. Phone Interview. 19 November 2008.]
It is hypothesized that the tip link is attached to the myosin motor which moves along
actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ov ...
filaments.
See also
*
Neuronal encoding of sound
References
Vestibular system
Auditory system
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