Titin
Template:PBB Titin, also known as connectin, is the largest known protein that is important in the contraction of striated muscle tissues.[1][2]
Structure
Titin is the largest known protein, consisting of 34,350 amino acids. The molecular weight of the mature protein is approximately 2,993,442.763 Da,[3] and it has a theoretical isoelectric point of 6.01.[4] The protein's empirical chemical formula is C132983H211861N36149O40883S693. It has a theoretical instability index (II) of 39.69, indicating that it would be stable in a test tube. The protein's in vivo half-life, the time it takes for half of the amount of protein in a cell to disappear after its synthesis in the cell, is predicted to be approximately 30 hours (in mammalian reticulocytes).[5]
Function
Titin is a large abundant protein of striated muscle. The protein is divided into two regions:
- N-terminal I-band
- is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine
- C-terminal A-band
- thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity.
A N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere respectively so that a Titin interacts with many sarcomeric proteins including:[6]your face
- Z line region: telethonin and alpha-actinin
- I band region: calpain-3 and obscurin
- M line region: myosin-binding protein C, calmodulin 1, CAPN3, and MURF1
your face
Linguistic significance
As the largest known protein, titin also has the longest IUPAC name. The full chemical name, which starts Methionyl... and ends ...isoleucine, contains 189,819 letters and is sometimes stated to be the longest word in the English language, or any language.[7] However, professional dictionary writers regard generic names of chemical compounds as verbal formulae rather than English words.[8]
Additional images
-
Sliding filament model of muscle contraction. (Titin labeled at upper right.)
References
- ^ Online Mendelian Inheritance in Man (OMIM): 188840
- ^ "Entrez Gene: TTN titin".
- ^ Result of Molecular Weight Calculation
- ^ "ExPASy-calculated pI for titin". Retrieved 2007-08-26.
- ^ "Swiss-Prot Protein knowledgebase, main entry". Retrieved 2006-05-04.
- ^ Bang ML, Centner T, Fornoff F, Geach AJ, Gotthardt M, McNabb M, Witt CC, Labeit D, Gregorio CC, Granzier H, Labeit S (2001). "The complete gene sequence of titin, expression of an unusual approximately 700-kDa titin isoform, and its interaction with obscurin identify a novel Z-line to I-band linking system". Circ. Res. 89 (11): 1065–72. doi:10.1161/hh2301.100981. PMID 11717165.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ "What is the longest word in the English language?". CliffsNotes.com. Retrieved 2009-05-26.
- ^ Oxford Word and Language Service team. "Ask the experts - What is the longest English word?". AskOxford.com / Oxford University Press. Retrieved 2008-01-13.
Further reading
External links
This article incorporates text from the United States National Library of Medicine, which is in the public domain.