Tenascins are

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix, is a three-dimensional network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide stru ...

glycoproteins Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...

. They are abundant in the

of developing

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

embryos An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sper ...

and they reappear around healing wounds and in the stroma of some

tumors A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

Types

There are four members of the tenascin gene family: tenascin-C, tenascin-R, tenascin-X and tenascin-W. * Tenascin-C is the founding member of the gene family. In the embryo it is made by migrating cells like the

neural crest Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn give rise to a diverse cell lineage—including melanocytes, craniofacial cartilage and bone, smooth muscle, per ...

; it is also abundant in developing

tendons A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

bone A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...

and

cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...

. *

Tenascin-R Tenascin-R is a protein that in humans is encoded by the ''TNR'' gene. Function Tenascin-R (TNR) is an extracellular matrix protein expressed primarily in the central nervous system. It is a member of the tenascin (TN) gene family, which inclu ...

is found in the developing and adult nervous system. *

Tenascin-X A member of the tenascin family, tenascin X (TN-X) also known as flexillin or hexabrachion-like protein is a 450kDa glycoprotein that is expressed in connective tissues. TN-X possesses a modular structure composed, from the N- to the C-terminal pa ...

is found primarily in loose connective tissue; mutations in the human tenascin-X gene can lead to a form of Ehlers-Danlos syndrome. * Tenascin-W is found in the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

and in developing bone. The basic structure is 14 EGF-like repeats towards the

N-terminal The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...

end, and 8 or more

fibronectin Fibronectin is a high- molecular weight (~500-~600 kDa) glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. Fibronectin also binds to other extracellular matrix proteins such as collage ...

-III domains which vary upon species and variant. Tenascin-C is the most intensely studied member of the family. It has anti-adhesive properties, causing cells in tissue culture to become rounded after it is added to the medium. One mechanism to explain this may come from its ability to bind to the extracellular matrix

glycoprotein Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...

and block fibronectin's interactions with specific

syndecans Syndecans are single transmembrane domain proteins that are thought to act as coreceptors, especially for G protein-coupled receptors. More specifically, these core proteins carry three to five heparan sulfate and chondroitin sulfate chains, i.e. ...

. The expression of tenascin-C in the stroma of certain tumors is associated with a poor prognosis.

References

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External links

* {{Fibrous proteins