Chondrocalcin comes from a family of pro-collagen molecules. This

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...

is found in the

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

and is involved in calcium-binding, which occurs in order to harden (or calcify) the cartilage. Another one of its roles is to assemble the triple collagen helix, which is predominately entails the linkage of

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...

and proline

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...

s and then the twisting of those linkages. Chondrocalcin is important because cartilage calcification of the growth plate is one of the main occurrences in endochondral bone formation. Because of its importance, it is one of the most highly created

polypeptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides ...

s in human cartilage. This

calcium-binding protein Calcium-binding proteins are proteins that participate in calcium cell signalling pathways by binding to Ca2+, the calcium ion that plays an important role in many cellular processes. Calcium-binding proteins have specific domains that bind to cal ...

comes from

chondrocyte Chondrocytes (, from Greek χόνδρος, ''chondros'' = cartilage + κύτος, ''kytos'' = cell) are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and prote ...

s, which are cells that produce and maintain cartilage. Some examples of chondrocytes include collagen and

proteoglycan Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to w ...

s. The chondrocytes that produce chondrocalcin are typically found in growing bone matrices that have not yet matured. These immature bone matrices are found in the

epiphyseal plate The epiphyseal plate (or epiphysial plate, physis, or growth plate) is a hyaline cartilage plate in the metaphysis at each end of a long bone. It is the part of a long bone where new bone growth takes place; that is, the whole bone is alive, wi ...

at both the lower hypertrophic zone and the longitudinal septa of the cartilaginous matrix. One study was conducted on fetal cartilage discovered that the chondrocalcin protein exists as a dimer with 35,000 g/mol subunits. The reason why fetal cartilage was used is because chondrocalcin cannot be detected in mature bone. Another investigation was conducted to determine the mechanism behind calcium binding in chondrocalcin. It was discovered that along with cartilage building, the protein also had a role in cartilage destruction.Poole AR et al
"Association of an Extracellular Protein (Chondrocalcin) with the Calcification of Cartilage in Endochondral Bone Formation
''Journal of Cell Biology.'', January 1984. Retrieved on 27 November 2017.

References

{{reflist Structural proteins