The tau protein is an important structural component inside the nerve. The following is an excellent explanation:
"Tau is abundant in neurons and binds to microtubulin where it has a pivotal role in microtubule growth and stability. And if it affects microtubule growth, then it affects not only cellular architecture but also cellular trafficking, since cells use microtubules as motorways to deliver nutrients and other molecules to different destinations. Without the assistance of tau, neurons are then neither able to elongate, nor to regenerate. In AD [Alzheimer's Disease], tau structure is modified via hyperphosphorylation and instead of assisting microtubulin, it creates tangled clumps of fibres in the neurone’s cytosol." (1)
The tau protein is critical to the structure of the nerve and the transportation system inside the nerve. When the tau protein is chemically altered, it loses its ability to connect with the nerve structure and then disrupts it. It is like collapsing bridges in a highway system. There is no way to cross the river and soon the nerve cell dies and disappears.
How is tau protein changed?
The DYRK1A gene instructs the cell to 'phosphoralate' the tau protein
Phosphorylation is the addition of a phosphate (PO4) to a protein or other organic molecule.
Phosphorylation activates or deactivates many protein enzymes.
The best theory is that having 1.5 times of the DYRK1A gene leads to' hyperphosphalation'. This means that phosphate groups (PO4) are added to the tau protein in an excessive manner. The result of this chemical change is that the tau protein falls off of the microtubules inside the nerve, clumps together and the nerve soon collapses.
Here is a video of this process. There is no sound but the animation is very good.
Next blog we will put the different pieces together.