lHeim_B

Tau6D phosphorylation.

AI Overview (Google's Gemini, March 26, 2026)

Yes, multiple phosphate (PO4) molecules can bind within the same functional regions or "pockets" of the tau protein, particularly in cases of hyperphosphorylation associated with Alzheimer’s disease.

Clustered Phosphorylation Sites: Tau is an intrinsically disordered protein (IDP) with about 85 potential phosphorylation sites. These sites are heavily clustered in the proline-rich region (residues 172-251) and the C-terminal tail (residues 368-441), which flank the microtubule-binding repeats. This high density means multiple phosphate groups often populate these regions simultaneously.
Binding Pocket Overlap: In the pathological, "hyperphosphorylated" state, the balance of kinases and phosphatases is disrupted, leading to the accumulation of many phosphate groups on a single tau molecule.
Specific Examples: Research shows that in Alzheimer’s diseased brains, hyperphosphorylated tau often has 5–9 phosphorylation sites modified, compared to only 2–3 in healthy adults.
Effect of Multiple Phosphates: The binding of multiple phosphates acts cumulatively. As more phosphate groups bind to tau, they remove the positive charge of the microtubule-binding region (MTBR), causing the tau protein to lose its affinity for microtubules, leading to aggregation.
Cooperative Binding: Phosphorylation at one site can sometimes prime or enhance phosphorylation at nearby sites within the same binding domain, facilitating the clustering of multiple phosphates.

In summary, the high concentration of potential sites in specific domains makes it likely that multiple phosphate groups reside in the same or closely positioned areas, directly causing the conformational changes that lead to pathology.

Order of binding	Receptor	Ligand	Affinity	Pocket ID	Residues that formed the binding pocket	Presence of SER, THR, TYR
1	Tau6D	PO4	-3.165	receptor_Tau6D_1	SER-602 ASN-603 VAL-604 GLN-605 SER-606 CYS-608 GLY-609 LYS-611 ASP-612	SER-602 SER-606
2	Tau6D	PO4	-2.809	receptor_Tau6D_12	LYS-692 LEU-693 THR-694 PHE-695 ARG-696 GLU-697	THR-694
3	Tau6D	PO4	-2.623	receptor_Tau6D_11	GLY-109 ASP-110 THR-111 VAL-368 ARG-370	THR-111
4	Tau6D	PO4	-2.538	receptor_Tau6D_1	SER-602 ASN-603 VAL-604 GLN-605 SER-606 CYS-608 GLY-609 LYS-611 ASP-612	SER-602 SER-606
5	Tau6D	PO4	-2.426	receptor_Tau6D_7	ASP-110 PRO-367 VAL-368 SER-369	SER-369
6	Tau6D	PO4	-2.371	receptor_Tau6D_1	SER-602 ASN-603 VAL-604 GLN-605 SER-606 CYS-608 GLY-609 LYS-611 ASP-612	SER-602 SER-606
7	Tau6D	PO4	-2.285	receptor_Tau6D_1	SER-602 ASN-603 VAL-604 GLN-605 SER-606 CYS-608 GLY-609 LYS-611 ASP-612	SER-602 SER-606
8	Tau6D	PO4	-2.158	receptor_Tau6D_2	ARG-487 ILE-488 PRO-489 ALA-490
9	Tau6D	PO4	-2.155	receptor_Tau6D_1	SER-602 ASN-603 VAL-604 GLN-605 SER-606 CYS-608 GLY-609 LYS-611 ASP-612	SER-602 SER-606