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Phosphoprotein phosphatase activities in Alzheimer disease brain
Gong CX, Singh TJ, Grundke-Iqbal I, Iqbal K.. Journal of neurochemistry, 1993-09-01
Topic: Amyloid, tau and blood-test diagnosis
Microtubule-associated protein tau is known to be hyperphosphorylated in Alzheimer disease brain and this abnormal hyperphosphorylation is associated with an inability of tau to promote the assembly of microtubule in the affected neurons. Our previous studies demonstrated that abnormally phosphorylated tau could be dephosphorylated after treatment with alkaline phosphatase, thereby suggesting that the abnormal phosphorylation of tau might in part be the result of a deficiency of the phosphoprotein phosphatase system in patients with Alzheimer disease. In the present study we used 32P-labeled phosphorylase kinase and poly(Glu, Tyr) 4:1 as substrates to measure phosphoprotein phosphatase activities in Alzheimer disease and control brains.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Gong, C. X., Singh, T. J., Grundke-Iqbal, I., & Iqbal, K. (1993). Phosphoprotein phosphatase activities in Alzheimer disease brain. Journal of neurochemistry. https://doi.org/10.1111/j.1471-4159.1993.tb03603.x
Vancouver
Gong CX, Singh TJ, Grundke-Iqbal I, Iqbal K. Phosphoprotein phosphatase activities in Alzheimer disease brain. Journal of neurochemistry. 1993. doi:10.1111/j.1471-4159.1993.tb03603.x. PMID: 8395566.
BibTeX
@article{gong1993-8395566,
author = {Gong, C. X. and Singh, T. J. and Grundke-Iqbal, I. and Iqbal, K.},
title = {{Phosphoprotein phosphatase activities in Alzheimer disease brain}},
journal = {Journal of neurochemistry},
year = {1993},
doi = {10.1111/j.1471-4159.1993.tb03603.x},
pmid = {8395566},
url = {https://doi.org/10.1111/j.1471-4159.1993.tb03603.x}
}
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Key findings
- Our previous studies demonstrated that abnormally phosphorylated tau could be dephosphorylated after treatment with alkaline phosphatase, thereby suggesting that the abnormal phosphorylation of tau might in part be the result of a deficiency of the phosphoprotein phosphatase system in patients with Alzheimer disease.
- In the present study we used 32P-labeled phosphorylase kinase and poly(Glu, Tyr) 4:1 as substrates to measure phosphoprotein phosphatase activities in Alzheimer disease and control brains.
- The activities of phosphoseryl/phosphothreonyl-protein phosphatase types 1, 2A, 2B, and 2C and of phosphotyrosyl-protein phosphatase in frontal gray and white matters from 13 Alzheimer brains were determined and compared with those from 12 age-matched control brains.
- The activities of type 1 phosphatase and phosphotyrosyl phosphatase in gray matter and of type 2A phosphatase in both gray and white matters were significantly lower in Alzheimer disease brains than in controls.
Why it matters
This study measured phosphoprotein phosphatase activity in postmortem brains and suggested that a deficiency in this system might contribute to abnormal tau phosphorylation in Alzheimer's disease. It describes a possible mechanism but does not test any treatment.
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Study details
- Evidence strengthLow
How this study scored 46/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on institution's track record, so that was left out: it earned 45 of the 97 points we could judge it on, which is 46 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Journal of neurochemistry) |
| Journal's citation record | 3 / 4 | Journal of Neurochemistry: journal h-index 349 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 1993 — older than 20 years, still counted |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 6 / 7 | Cited 530 times (OpenAlex, 2026-10-10) |
| Citations per year | 3 / 5 | 15.1 citations a year over 35 year(s) since 1993 |
| Impact for its field and year | 3 / 6 | Cited 6.4× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 3 / 6 | Cited by 18 other studies in this library |
| Still being cited | 2 / 4 | Cited 35 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Khalid Iqbal: h-index 112 (OpenAlex, whole career) |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | 0 / 3 | OpenAlex lists 0 institution(s) in 0 countries — scores zero (affiliation lists can be incomplete) |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 8395566) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 45 / 97 | Scored on 19 of 20 parts. We have no data for the rest, so they are left out: 45 of the 97 points we could judge it on is 46 out of 100. |
| Total | 46 / 100 | — |
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