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] Fosforylering, de toevoeging van een fosfaatgroep is een belangrijke wijziging voor cellen om de eiwitfunctie te reguleren. Wanneer een fosfaatgroep wordt verwijderd tijdens ATP-hydrolyse, kunnen enzymen die proteïne kinasen worden genoemd, de covalente binding van deze groep aan bepaalde aminozuur zijketens in een eiwit katalyseren. Als gevolg daarvan verandert het eiwit van vorm of laat het andere eiwitten zich binden aan de gefosforyleerde gebieden.

Deze veranderingen kunnen de functie van een eiwit wijzigen en kunnen het zelfs volledig activeren of deactiveren. De fosfaatgroep kan worden verwijderd door de werking van eiwitfosfatase, enzymen die de defosforylering van eiwitten katalyseren, waardoor de reactie in wezen wordt omgekeerd. Door de fosforylering op deze manier te reguleren kan de activiteit van bepaalde eiwitten omkeerbaar worden aangezet, uitgeschakeld of gewijzigd als dat nodig is in de cel.

fosforylatie

De toevoeging of verwijdering van fosfaatgroepen aan eiwitten is de meest voorkomende chemische modificatie die cellulaire processen reguleert. Deze modificaties kunnen de structuur, activiteit, stabiliteit en lokalisatie van eiwitten in cellen beïnvloeden, evenals hun interacties met andere eiwitten.

Tijdens fosforylatie dragen proteïnekinasen de terminale fosfaatgroep van adenosinetrifosfaat (ATP) over naar specifieke aminozuurzijketens van substraateiwitten. Serine, threonine en tyrosine zijn de meest voorkomende gefosforyleerde aminozuren. Dienovereenkomstig worden proteïnekinasen geclassificeerd als: Serine/threoninekinasen, Tyrosinekinasen, Kinasen met dubbele werking (die alle drie de aminozuren kunnen fosforyleren), Omgekeerd katalyseren eiwitfosfatasen de verwijdering van de fosfaatgroep (defosforylering), waardoor de oorspronkelijke eigenschappen van het eiwit worden hersteld.

Onder fysiologische omstandigheden worden fosforylatie en defosforylering strak gereguleerd om langdurige veranderingen in de eiwitstructuur en -functie te voorkomen. Verstoring van dit evenwicht kan ziekten veroorzaken, waaronder kanker en verschillende neurodegeneratieve aandoeningen. Een voorbeeld hiervan is het tau-eiwit, dat hypergefosforyleerd is bij de ziekte van Alzheimer (AD). Fysiologisch reguleert tau de vorm, structuur en ontwikkeling van neuronen. Het tau-eiwit bevat meer dan 80 serine-, threonine- en tyrosineresiduen, waarvan normaal gesproken slechts een fractie gefosforyleerd is. In de hersenen van patiënten met AD wordt tau abnormaal en overmatig gefosforyleerd. Dit verandert de buffersysteem van het eiwit, wat leidt tot de vorming van giftige, onoplosbare aggregaten die uiteindelijk neuronaal celverlies veroorzaken.

Fosforylatie

The addition or removal of phosphate groups from proteins is the most common chemical modification that regulates cellular processes. These modifications ...

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KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

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

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.

Phosphorylation and Protein Control | JoVE K12

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Phosphorylation and Protein Control

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