Titin Structure & Function
From Proteopedia
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| - | Titin is a polypeptide chain protein which is greater than 1µm in length and 3-4 nm in width <ref name=journal1>PMID:14506471</ref>. The protein molecule has a molecular weight of up to approximately 4 Mda. Titin is a multidomain structure that which is found to be composed of two types of domains similar to immunoglobulin (Ig) and fibronectin.<ref name= | + | Titin is a polypeptide chain protein which is greater than 1µm in length and 3-4 nm in width <ref name=journal1>PMID:14506471</ref>. The protein molecule has a molecular weight of up to approximately 4 Mda. Titin is a multidomain structure that which is found to be composed of two types of domains similar to immunoglobulin (Ig) and fibronectin.<ref name=journal2/> There are approximately Ig and fibronectin domains present in titin, with also kinase domains close to the carboxyl terminus.<ref name=journal1/> These two types of domains are β-sandwiches of seven or eight strands that are made of about 100 residues.<ref name=journal1/> The carboxyl terminus is in the head region of a titin molecule.<ref name=journal1/> The structure also contains specialized binding sites and a putative elastic region, the PEVK domain, and there is a unique sequence region part of a titin molecule <ref name=journal2>PMID:9153398</ref>. The multidomain structure is evident by the interdomain periodicity seen in the structure.<ref name=journal1/> A titin molecule is half a sacromeres size with the four regions of the I-band,the A-band, the M-line and the Z-line. <ref name=journal1/> The I-band section of the titin is made up of only Ig domains and unique sequences with the Ig domains arranged in tandem.<ref name=journal1/> The A-band section is the largest part of the protein molecule with a highly conserved sequence.<ref name=journal1/> In the A-band section the Ig and fibronectin domains are set up in a long range pattern and are called the super repeats. There are two types of the Ig and fibronectin sets that are arranged in long range patterns, made from either seven and eleven domains. Located near the end of the A-band there are six copies of small super repeats, that which are 25-30 nm long. <ref name=journal1/> The M-line contains the overlapped carboxyl terminus regions of the titin molecule. <ref name=journal1/> The Z-line region is on the opposite end which has the overlapped amino terminal regions of a molecule from the neighboring sacromere.<ref name=journal1/> |
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Titin seems to be a key component in the assembly and functioning of vertebrates straited muscles.<ref name=journal1/> It has regions that mirror the different parts of the sacromere, which have mechanical functions, catalytic functions and the ability to bind many other sacromere proteins. <ref name=journal1/> | Titin seems to be a key component in the assembly and functioning of vertebrates straited muscles.<ref name=journal1/> It has regions that mirror the different parts of the sacromere, which have mechanical functions, catalytic functions and the ability to bind many other sacromere proteins. <ref name=journal1/> | ||
| - | Titin is responsible for the elasticity of relaxed striated muscles and acts as the molecular scaffold for thick filament formation. It generates most of the elastic response of a sacromere, which responds like a bidirectional spring which stretches and recoils during movement of muscles to cause the myofibril to go back to its resting state <ref name= | + | Titin is responsible for the elasticity of relaxed striated muscles and acts as the molecular scaffold for thick filament formation. It generates most of the elastic response of a sacromere, which responds like a bidirectional spring which stretches and recoils during movement of muscles to cause the myofibril to go back to its resting state <ref name=journal3>PMID:18212128</ref>. In mature muscle, titin molecules have a part in the mechanisms that control elasticity and the operating range (the length range of sacromeres when they shorten and extend in muscle in vivo) of sacromere lengths and tension-related processes in the body. <ref name=journal1/> A primary function of titin is giving elastic stabilization of relative positions of myosin and actin filaments.<ref name=journal1/> |
= References = | = References = | ||
<references/> | <references/> | ||
Revision as of 18:26, 31 March 2010
Titin, also known as connectin, is a flexible intrasarcomeric filamentous protein, which is largest proteins known today.
Overall Structure
Titin is a polypeptide chain protein which is greater than 1µm in length and 3-4 nm in width [1]. The protein molecule has a molecular weight of up to approximately 4 Mda. Titin is a multidomain structure that which is found to be composed of two types of domains similar to immunoglobulin (Ig) and fibronectin.[2] There are approximately Ig and fibronectin domains present in titin, with also kinase domains close to the carboxyl terminus.[1] These two types of domains are β-sandwiches of seven or eight strands that are made of about 100 residues.[1] The carboxyl terminus is in the head region of a titin molecule.[1] The structure also contains specialized binding sites and a putative elastic region, the PEVK domain, and there is a unique sequence region part of a titin molecule [2]. The multidomain structure is evident by the interdomain periodicity seen in the structure.[1] A titin molecule is half a sacromeres size with the four regions of the I-band,the A-band, the M-line and the Z-line. [1] The I-band section of the titin is made up of only Ig domains and unique sequences with the Ig domains arranged in tandem.[1] The A-band section is the largest part of the protein molecule with a highly conserved sequence.[1] In the A-band section the Ig and fibronectin domains are set up in a long range pattern and are called the super repeats. There are two types of the Ig and fibronectin sets that are arranged in long range patterns, made from either seven and eleven domains. Located near the end of the A-band there are six copies of small super repeats, that which are 25-30 nm long. [1] The M-line contains the overlapped carboxyl terminus regions of the titin molecule. [1] The Z-line region is on the opposite end which has the overlapped amino terminal regions of a molecule from the neighboring sacromere.[1]
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Function
Titin seems to be a key component in the assembly and functioning of vertebrates straited muscles.[1] It has regions that mirror the different parts of the sacromere, which have mechanical functions, catalytic functions and the ability to bind many other sacromere proteins. [1] Titin is responsible for the elasticity of relaxed striated muscles and acts as the molecular scaffold for thick filament formation. It generates most of the elastic response of a sacromere, which responds like a bidirectional spring which stretches and recoils during movement of muscles to cause the myofibril to go back to its resting state [3]. In mature muscle, titin molecules have a part in the mechanisms that control elasticity and the operating range (the length range of sacromeres when they shorten and extend in muscle in vivo) of sacromere lengths and tension-related processes in the body. [1] A primary function of titin is giving elastic stabilization of relative positions of myosin and actin filaments.[1]
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 Tskhovrebova L, Trinick J. Titin: properties and family relationships. Nat Rev Mol Cell Biol. 2003 Sep;4(9):679-89. PMID:14506471 doi:10.1038/nrm1198
- ↑ 2.0 2.1 Tskhovrebova L, Trinick J, Sleep JA, Simmons RM. Elasticity and unfolding of single molecules of the giant muscle protein titin. Nature. 1997 May 15;387(6630):308-12. PMID:9153398 doi:10.1038/387308a0
- ↑ von Castelmur E, Marino M, Svergun DI, Kreplak L, Ucurum-Fotiadis Z, Konarev PV, Urzhumtsev A, Labeit D, Labeit S, Mayans O. A regular pattern of Ig super-motifs defines segmental flexibility as the elastic mechanism of the titin chain. Proc Natl Acad Sci U S A. 2008 Jan 29;105(4):1186-91. Epub 2008 Jan 22. PMID:18212128
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