Wednesday, August 24, 2011

Tau Protein Definition ~ Top 8 Definition of Tau Protein ~ Tau Protein Blog


Tau Protein Definition ~ Top 8 Definition of Tau Protein ~ Tau Protein Blog

Tau Protein Definition-I: A protein found in the axons of healthy neurons, where it binds to other proteins called microtubules to form the cytoskeleton of the neuron and provide the tracks over which material can be transported from one part of the neuron to another. http://www.answers.com/topic/tau-protein#ixzz1Vx45TwC7
Tau Protein Definition-II: Protein (60-70 kD) that co purifies with tubulin through cycles of assembly and disassembly and the first microtubule associated protein to be characterised. Tau proteins are a family made by alternative splicing of a single gene. It has tandem repeats of a tubulin binding domain and promotes tubulin assembly. Although tau proteins are found in all cells they are major components of neurons where they are predominantly associated with microtubules of the axon. See: MAPs. This entry appears with permission from the Dictionary of Cell and Molecular Biology (11 Mar 2008): http://www.lexic.us/definition-of/tau_protein
Tau Protein Definition-III
(Biochemistry) a protein that maintains the stability of the microtubules that serve as a transport system within brain cells. It is also implicated in the formation of masses of fibrous protein in the brains of people with Alzheimer’s disease. http://www.science-dictionary.com/definition/tau-protein.html
Tau Protein Definition-IV  
A microtubule-associated protein that forms insoluble and hyperphosphorylated aggregates in Alzheimer's disease. http://medical-dictionary.thefreedictionary.com/tau+protein

Tau Protein Definition-V  
(Science: cell biology) protein (60-70 kD) that co purifies with tubulin through cycles of assembly and disassembly and the first microtubule associated protein to be characterised. Tau proteins are a family made by alternative splicing of a single gene. It has tandem repeats of a tubulin binding domain and promotes tubulin assembly. Although tau proteins are found in all cells they are major components of neurons where they are predominantly associated with microtubules of the axon. http://www.biology-online.org/dictionary/Tau_protein

Tau Protein Definition-VI  
Microtubule-associated proteins that are mainly expressed in neurons. Tau proteins constitute several isoforms and play an important role in the assembly of tubulin monomers into microtubules and in maintaining the cytoskeleton and axonal transport. Aggregation of specific sets of tau proteins in filamentous inclusions is the common feature of intraneuronal and glial fibrillar lesions (NEUROFIBRILLARY TANGLES; NEUROPIL THREADS) in numerous neurodegenerative disorders (ALZHEIMER DISEASE; TAUOPATHIES). http://medconditions.net/tau-protein.html

Tau Protein Definition-VII  
Microtubule-associated proteins that are mainly expressed in neurons. Tau proteins constitute several isoforms and play an important role in the assembly of tubulin monomers into microtubules and in maintaining the cytoskeleton and axonal transport. Aggregation of specific sets of tau proteins in filamentous inclusions is the common feature of intraneuronal and glial fibrillar lesions (NEUROFIBRILLARY TANGLES; NEUROPIL THREADS) in numerous neurodegenerative disorders (ALZHEIMER DISEASE; TAUOPATHIES). http://www.reference.md/files/D016/mD016875.html
Tau Protein Definition-VIII  
Tau proteins are proteins that stabilize microtubules. They are abundant in neurons in the central nervous system and are less common elsewhere. When tau proteins are defective, and no longer stabilize microtubules properly, they can result in dementias such as Alzheimer's disease.
The tau proteins are the product of alternative splicing from a single gene that in humans is designated MAPT (microtubule-associated protein tau).[1][2] They were discovered in 1975 in Marc Kirschner's laboratory at Princeton University.
Function
Tau proteins interact with tubulin to stabilize microtubules and promote tubulin assembly into microtubules. Tau has two ways of controlling microtubule stability: isoforms and phosphorylation.
Six tau isoforms exist in human brain tissue, and they are distinguished by their number of binding domains. Three isoforms have three binding domains and the other three have four binding domains. The binding domains are located in the carboxy-terminus of the protein and are positively-charged (allowing it to bind to the negatively-charged microtubule). The isoforms with four binding domains are better at stabilizing microtubules than those with three binding domains. The isoforms are a result of alternative splicing in exons 2, 3, and 10 of the tau gene.
Phosphorylation of tau is regulated by a host of kinases, including PKN, a serine/threonine kinase. When PKN is activated, it phosphorylates tau, resulting in disruption of microtubule organization.[4]
Tau protein is a highly soluble microtubule-associated protein (MAP). In humans, these proteins are mostly found in neurons compared to non-neuronal cells. One of tau's main functions is to modulate the stability of axonal microtubules. Tau is not present in dendrites and is active primarily in the distal portions of axons where it provides microtubule stabilization but also flexibility as needed. This contrasts with MAP6 (STOP) proteins in the proximal portions of axons which essentially lock down the microtubules and MAP2 that stabilizes microtubules in dendrites.
Genetics
The MAPT gene for encoding tau protein is located on chromosome 17q21, containing 16 exons. The major tau protein in the human brain is encoded by 11 exons. Exons 2, 3 and 10 are alternatively spliced, allowing six combinations (2–3–10–; 2+3–10–; 2+3+10–; 2–3–10+; 2+3–10+; 2+3+10+). Thus, in the human brain, the tau proteins constitute a family of six isoforms with the range from 352-441 amino acids. They differ in either zero, one or two inserts of 29 amino acids at the N-terminal part (exon 2 and 3), and three or four repeat-regions at the C-terminal part exon 10 missing. So, the longest isoform in the CNS has four repeats (R1, R2, R3 and R4) and two inserts (441 amino acids total), while the shortest isoform has three repeats (R1, R3 and R4) and no insert (352 amino acids total).
The MAPT gene has two haplogroups, H1 and H2, in which the gene appears in inverted orientations. Haplogroup H2 is common only in Europe and in people with European ancestry. Haplogroup H1 appears to be associated with increased probability of certain dementias, such as Alzheimer's disease. The presence of both haplogroups in Europe means that recombination between inverted haplotypes can result in the lack of one of the functioning copy of the gene, resulting in congenital defects.[5][6][7][8]
Tauopathy
Hyperphosphorylation of the tau protein (tau inclusions, pTau) can result in the self-assembly of tangles of paired helical filaments and straight filaments, which are involved in the pathogenesis of Alzheimer's disease and other tauopathies.
All of the six tau isoforms are present in an often hyperphosphorylated state in paired helical filaments from Alzheimer's disease brain. In other neurodegenerative diseases, the deposition of aggregates enriched in certain tau isoforms has been reported. When misfolded, this otherwise very soluble protein can form extremely insoluble aggregates that contribute to a number of neurodegenerative diseases. http://en.wikipedia.org/wiki/Tau_protein

1 comment:

  1. Is there a way to find or determine in live humans if hyperphosphorylation and/or tau inclusions are present?
    Do you know if there is any research that shows how or if the body can digest or re-absorb these protiens once they are formed within the brain or nerve system?

    ReplyDelete