Chemosensory clusters

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Chemosensory clusters are aggregates formed by a small number of chemoreceptor cells with characteristics similar to those found in the taste cells of the oropharyngeal cavity. The chemosensory clusters are similar to the taste buds but are smaller, resembling the developing taste buds. Chemosensory clusters are located in the larynx distally to the portion in which are present laryngeal taste buds and proximally to the region in which solitary chemosensory cells are found. Rarely, chemosensory clusters may be found in the distal portion of the airway.

The elements forming the chemosensory clusters share common morphological and biochemical characteristics with the taste cells located in taste buds of the oropharyngeal cavity. In particular, they may express molecules of the chemoreceptorial cascade (e.g. trans-membrane taste receptors, the G-protein gustducin, PLCbeta2, IP3R3, TRPM5). Usually, in chemosensory cluster a true "taste pore" is lacking.

To date, the functional role of the chemosensory clusters is unknown.

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Related Research Articles

A chemoreceptor, also known as chemosensor, is a specialized sensory receptor cell which transduces a chemical substance to generate a biological signal. This signal may be in the form of an action potential, if the chemoreceptor is a neuron, or in the form of a neurotransmitter that can activate a nerve fiber if the chemoreceptor is a specialized cell, such as taste receptors, or an internal peripheral chemoreceptor, such as the carotid bodies. In physiology, a chemoreceptor detects changes in the normal environment, such as an increase in blood levels of carbon dioxide (hypercapnia) or a decrease in blood levels of oxygen (hypoxia), and transmits that information to the central nervous system which engages body responses to restore homeostasis.

Gustducin is a G protein associated with taste and the gustatory system, found in some taste receptor cells. Research on the discovery and isolation of gustaducin is recent. It is known to play a large role in the transduction of bitter, sweet and umami stimuli. Its pathways are many and diverse.

TRPM5

Transient receptor potential cation channel subfamily M member 5 (TRPM5), also known as long transient receptor potential channel 5 is a protein that in humans is encoded by the TRPM5 gene.

TAS2R1

Taste receptor type 2 member 1 (TAS2R1/T2R1) is a protein that in humans is encoded by the TAS2R1 gene. It belongs to the G protein-coupled receptor (GPCR) family and is related to class A-like GPCRs, they contain 7 transmembrane helix bundles and short N-terminus loop. Furthermore, TAS2R1 is member of the 25 known human bitter taste receptors, which enable the perception of bitter taste in the mouth cavity. Increasing evidence indicates a functional role of TAS2Rs in extra-oral tissues.

TAS2R3

Taste receptor type 2 member 3 is a protein that in humans is encoded by the TAS2R3 gene.

TAS2R8

Taste receptor type 2 member 8 is a protein that in humans is encoded by the TAS2R8 gene.

TAS2R9

Taste receptor type 2 member 9 is a protein that in humans is encoded by the TAS2R9 gene.

TAS2R10

Taste receptor type 2 member 10 is a protein that in humans is encoded by the TAS2R10 gene.

TAS2R13

Taste receptor type 2 member 13 is a protein that in humans is encoded by the TAS2R13 gene.

TAS2R5

Taste receptor type 2 member 5 is a protein that in humans is encoded by the TAS2R5 gene.

TAS2R7

Taste receptor type 2 member 7 is a protein that in humans is encoded by the TAS2R7 gene.

TAS1R3

Taste receptor type 1 member 3 is a protein that in humans is encoded by the TAS1R3 gene. The TAS1R3 gene encodes the human homolog of mouse Sac taste receptor, a major determinant of differences between sweet-sensitive and -insensitive mouse strains in their responsiveness to sucrose, saccharin, and other sweeteners.

TAS2R39

Taste receptor type 2 member 39 is a protein that in humans is encoded by the TAS2R39 gene.

TAS2R40

Taste receptor type 2 member 40 is a protein that in humans is encoded by the TAS2R40 gene.

TAS2R45

Taste receptor type 2 member 45 is a protein that in humans is encoded by the TAS2R45 gene.

TAS2R30 Protein-coding gene in humans

Taste receptor type 2 member 30 is a protein that in humans is encoded by the TAS2R30 gene.

TAS2R19

Taste receptor type 2 member 19 is a protein that in humans is encoded by the TAS2R19 gene. It seems to be involved in the perception of salt and bitter tastes.

TAS2R60

Taste receptor type 2 member 60 is a protein that in humans is encoded by the TAS2R60 gene.

The diffuse chemosensory system (DCS) is an anatomical structure composed of solitary chemosensory cells and chemosensory clusters. The concept of DCS has been advanced in 2005, after the discovery that cells similar to gustatory elements are present in several organs of the respiratory and digestive apparatuses.

Solitary chemosensory cells (SCCs) are isolated elements located in epithelia of the apparatuses of endodermic origin. In the aquatic vertebrates, SCCs are also present in the skin. In oral cavity, SCCs precedes the development of taste buds. For long time, SCCs were considered to be typical of aquatic vertebrates. Recently, these elements were also demonstrated in mammals.

References

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