lHeim_B

Tau1C 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	Tau1C	PO4	-2.917	receptor_Tau1C_13	MET-736 VAL-737 ASP-738 SER-739 PRO-740 LEU-742 ALA-743	SER-739
2	Tau1C	PO4	-2.72	receptor_Tau1C_1	ARG-723 HIS-724 LEU-725 SER-726 ASN-727 VAL-728	SER-726
3	Tau1C	PO4	-2.646	receptor_Tau1C_7	VAL-604 GLN-605 SER-606 GLY-609 SER-610 LYS-611 ASP-612	SER-606 SER-610
4	Tau1C	PO4	-2.57	receptor_Tau1C_9	GLU-659 LYS-660 LEU-661 ASP-662 PHE-663 ARG-666 VAL-667
5	Tau1C	PO4	-2.514	receptor_Tau1C_17	PHE-695 ARG-696 GLU-697 ALA-699 LYS-700 ALA-701 THR-703 HIS-705 ALA-707 GLU-708 ILE-709 TYR-711	THR-703 TYR-711
6	Tau1C	PO4	-2.598	receptor_Tau1C_17	PHE-695 ARG-696 GLU-697 ALA-699 LYS-700 ALA-701 THR-703 HIS-705 ALA-707 GLU-708 ILE-709 TYR-711	THR-703 TYR-711
7	Tau1C	PO4	-2.781	receptor_Tau1C_17	PHE-695 ARG-696 GLU-697 ALA-699 LYS-700 ALA-701 THR-703 HIS-705 ALA-707 GLU-708 ILE-709 TYR-711	THR-703 TYR-711
8	Tau1C	PO4	-2.714	receptor_Tau1C_17	PHE-695 ARG-696 GLU-697 ALA-699 LYS-700 ALA-701 THR-703 HIS-705 ALA-707 GLU-708 ILE-709 TYR-711	THR-703 TYR-711
9	Tau1C	PO4	-3.038	receptor_Tau1C_17	PHE-695 ARG-696 GLU-697 ALA-699 LYS-700 ALA-701 THR-703 HIS-705 ALA-707 GLU-708 ILE-709 TYR-711	THR-703 TYR-711