Target type: cellularcomponent
An actin-based protrusion from the apical surface of auditory and vestibular hair cells and of neuromast cells. These protrusions are supported by a bundle of cross-linked actin filaments (an actin cable), oriented such that the plus (barbed) ends are at the tip of the protrusion, capped by a tip complex which bridges to the plasma. Bundles of stereocilia act as mechanosensory organelles. [GOC:ecd, PMID:15661519, PMID:7840137]
Stereocilia are hair-like projections on the apical surface of hair cells, which are specialized sensory cells found in the inner ear. They are responsible for detecting sound vibrations and converting them into electrical signals that the brain can interpret. The cellular component of stereocilia can be broadly divided into two major categories: the **actin core** and the **associated proteins**.
**Actin core:** This is the structural foundation of stereocilia, providing them with their rigid, hair-like shape. The actin core is composed of a tightly packed bundle of actin filaments, arranged in a parallel fashion. These filaments are interconnected by cross-linking proteins, such as **fimbrin and espin**, which maintain the proper spacing and organization of the filaments.
**Associated proteins:** These proteins are intimately associated with the actin core and play crucial roles in regulating stereocilia morphology, stability, and function. Some key associated proteins include:
* **Myosin VIIa:** A motor protein that transports and assembles actin filaments at the stereocilia tip.
* **Harmonin:** A scaffolding protein that links the actin core to the cell membrane.
* **Cadherin 23:** A transmembrane protein that provides lateral adhesion between stereocilia.
* **Protocadherin 15:** Another transmembrane protein that contributes to stereocilia adhesion and regulates their length.
* **Sans:** A protein that regulates the length and stability of stereocilia by interacting with the actin core.
* **USH2A:** A protein that is crucial for the proper development and maintenance of stereocilia. Mutations in this gene can lead to Usher syndrome, a genetic disorder that causes hearing loss and vision impairment.
The intricate arrangement and interaction of these components within the stereocilium ensure its proper structure, function, and stability. Any disruption in this intricate system can lead to hearing impairment.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Unconventional myosin-XV | A myosin-XV that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9UKN7] | Homo sapiens (human) |
| Adenylate cyclase type 6 | An adenylate cyclase type 6 that is encoded in the genome of human. [PRO:DNx, UniProtKB:O43306] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| sch 23390 | SCH 23390 : A benzazepine that is 2,3,4,5-tetrahydro-3-benzazepine bearing a phenyl substituent at position 1, a methyl substituent at position 3, a chloro substituent at position 7 and a hydroxy substituent at position 8. SCH 23390: a selective D1-receptor antagonist | benzazepine | |
| blister | blebbistatin : A pyrroloquinoline that is 1,2,3,3a-tetrahydro-H-pyrrolo[2,3-b]quinolin-4-one substituted by a hydroxy group at position 3a, a methyl group at position 6 and a phenyl group at position 1. It acts as an inhibitor of ATPase activity of non-muscle myosin II. blebbistatin: structure in first source | cyclic ketone; pyrroloquinoline; tertiary alcohol; tertiary alpha-hydroxy ketone | inhibitor |
| sk&f-38393 | (R)-SKF 38393 : A 1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol that is the R-enantiomer of SKF 38393. | 1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol |