Osteopontin
| Osteopontin | ||
|---|---|---|
| Properties of human protein | ||
| Mass / length primary structure | 298 amino acids | |
| Isoforms | OPN-a, OPN-b, OPN-c, others | |
| Identifier | ||
| Gene name | SPP1 | |
| External IDs | ||
| Occurrence | ||
| Homology family | Osteopontin | |
| Parent taxon | Higher mammals | |
Osteopontin (OPN) (gene: SPP1 ) is a protein in all higher mammals that is involved in the maintenance of bone substance and some immune processes. It binds hydroxyapatite and provides the basic structure (matrix) for bones, but also for kidney stones .
It is encoded by a gene of the same name , which is located in the long arm of human chromosome 4q . Osteopontin belongs to the family of so-called " siblings " ( s mall i integrin b inding li gand N -linked g lycoprotein ), with whose members it has genetic and biochemical similarities.
Osteopontin was discovered as a glycoprotein in osteoblasts in 1986 and consists of around 300 amino acids .
The prefix osteo indicates that the protein is made in bone tissue. As an extracellular structural protein, osteopontin is part of the bone marrow and the bone matrix (see also bones ). Synonymous names of the protein are sialoprotein I and 44K BPP (English bone phosphoprotein ). One functional characteristic is the ability to bind to integrins . This property is conveyed through the RGD motif .
Osteopontin occurs in a variety of tissue types such as osteoblasts, osteocytes , the inner ear, the brain, the kidneys, the placenta , odontoblasts , some bone marrow cells, cartilage cells , macrophages , smooth muscle cells , and endothelial cells . The formation of osteopontin is stimulated by calcitriol (1,25-dihydroxy-vitamin-D3).
Osteopontin may at various cancers such as lung cancer , breast cancer , colon cancer , stomach cancer , ovarian cancer , skin cancer and pleural mesothelioma be overexpressed . It is also involved in the development of kidney stones .
Tumors do not grow in isolation; they need new blood vessels to supply oxygen, nutrients and supporting tissue. Signals that promote tumor growth are transmitted over long distances throughout the body. One of the messenger substances involved is the protein osteopontin. Cancer patients with aggressive tumors have very high levels of osteopontin in their blood serum .
When multiple sclerosis , especially with the relapsing form, osteopontin seems to play an important role. Studies have found that osteopontin levels are increased shortly before and during an attack. In addition, the protein appears to have a positive effect on the lifespan of autoimmune T cells , which are held responsible for the disease, by inhibiting the natural apoptosis of these cells.
Web links
- What prepares the ground for cancer. On: Wissenschaft.de from June 13, 2008.
Individual evidence
- ↑ Bellahcène A, Castronovo V, Ogbureke KU, Fisher LW, Fedarko NS: Small integrin-binding ligand N-linked glycoproteins (SIBLINGs): multifunctional proteins in cancer . In: Nat. Rev. Cancer . 8, No. 3, March 2008, pp. 212-226. doi : 10.1038 / nrc2345 . PMID 18292776 . PMC 2484121 (free full text).
- ↑ Protein causes flare-ups . from pharmische-zeitung.de, accessed on April 5, 2011
- ↑ Steinman L .: Shifting therapeutic attention in MS to osteopontin, type 1 and type 2 IFN . In: Eur J Immunol. . September 2009. PMID 18292776 .