Name: phosphorylation and protein control
Uploaded: 2019-03-11T09:21:10.000Z
Duration: 1 min 2 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Life Science

LS.4

LS.4.b

Phosphorylation

- [Instructeur] La phosphorylation,l'addition de groupes phosphate,est une modification importante permettant aux cellulesde réguler la fonction des protéines. 
Quand un groupe phosphate est retirélors de l'hydrolyse de l'ATP,des enzymes appelées "protéines kinases"peuvent catalyser la liaison covalente de ce groupeà certaines chaînes latérales d'acides aminésdans une protéine. 
Ainsi, la protéine change de formeou permet à d'autres protéinesde se fixer aux zones phosphorylées. 
Ces changements peuvent modifier la fonction d'une protéine,et même l'activer ou la désactiver totalement. 
Le groupe phosphate peut être retirégrâce à l'action des protéines phosphatases,ces enzymes qui catalysentle déphosphorylation des protéines,ce qui inverse en fait la réaction. 
En régulant la phosphorylation de cette manière,l'activité de certaines protéines peut être réversiblementactivée, désactivéeou modifiée selon les besoins dans la cellule.

Kyriakis, John M. « Au commencement, il y avait phosphorylation des protéines ». Le Journal de chimie biologique 289, n° 14 (4 avril 2014) : 9460-62. [<a href="https://doi.org/10.1074/jbc.R114.557926 » target="__blank">Source</a>]
Ardito, Fatima, Michele Giuliani, Donatella Perrone, Giuseppe Troiano et Lorenzo Lo Muzio. « Le rôle crucial de la phosphorylation des protéines dans la signalisation cellulaire et son utilisation en tant que thérapie ciblée (revue). » International Journal of Molecular Medicine 40, n° 2 (août 2017) : 271-80. [<a href="https://doi.org/10.3892/ijmm.2017.3036 » target="__blank">Source</a>]

phosphorylation

L’addition ou l’élimination de groupes phosphates des protéines est la modification chimique la plus courante qui régule les processus cellulaires. Ces modifications peuvent affecter la structure, l’activité, la stabilité et la localisation des protéines dans les cellules ainsi que leurs interactions avec d’autres protéines. 
 
 Pendant la phosphorylation, les protéines kinases transfèrent le groupe phosphate terminal de l’ATP aux chaînes latérales d’acides aminés spécifiques de protéines substrats. La sérine, la thréonine et la tyrosine sont les acides aminés les plus fréquemment phosphorylés. Par conséquent, les protéines kinases sont classées en tant que kinases de sérine/thréonine, kinases de tyrosine, ou kinases à double action si elles peuvent phosphoryler les trois acides aminés. Inversement, les protéines phosphatases catalysent l’élimination du groupe phosphate (déphosphorylation), rétablissant les propriétés d’origine de la protéine.
 
 Dans des conditions physiologiques, la phosphorylation et la déphosphorylation sont étroitement régulées pour empêcher les changements prolongés dans la structure et la fonction des protéines. La perturbation de cet équilibre peut provoquer des maladies, y compris le cancer et divers troubles neurodégénératifs. Par exemple, une protéine nommée tau est hyperphosphorylée dans la maladie d’Alzheimer (MA). Physiologiquement, tau régule la forme, la structure et le développement des neurones. La protéine tau contient plus de 80 résidus de sérine, de thréonine et de tyrosine, dont seulement une fraction est habituellement phosphorylée. Dans le cerveau des patients atteints de la MA, tau est anormalement et excessivement phosphorylé. Cela altère la solubilité de la protéine, formant des agrégats insolubles toxiques qui mènent à la mort neuronale.

L’ajout ou l’élimination de groupes phosphate dans les protéines est la modification chimique la plus courante qui régule les processus cellulaires. Ces modifications ...

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phosphorylation and protein control

Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins.

During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often phosphorylated are serine, threonine, and tyrosine. Protein kinases are grouped as serine/threonine kinases, tyrosine kinases, or dual action kinases when they can phosphorylate all three.

Protein phosphatases carry out the reverse step. They remove the phosphate group in a process called dephosphorylation, which restores the protein’s original properties. In healthy cells, phosphorylation and dephosphorylation are carefully balanced so protein shape and function do not stay changed for too long.

When this balance is disrupted, disease can result. Examples include cancer and several neurodegenerative disorders. Tau is one important example. In healthy neurons, tau helps regulate neuron shape, structure, and development. Tau has more than 80 serine, threonine, and tyrosine sites, but only some are normally phosphorylated. In Alzheimer’s disease, tau becomes hyperphosphorylated, or abnormally over-phosphorylated. This makes the protein less soluble and leads to toxic insoluble aggregates that contribute to neuronal death.

Phosphorylation and Protein Control

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Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins. During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often...

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key terms and concepts

Learn how kinases add phosphate groups, phosphatases remove them, and why balanced phosphorylation matters for cell function and diseases like Alzheimer’s.

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Phosphorylation and Protein Control

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