GSK-3β Protein

GSK-3β Protein

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2">GSK-3β (Glycogen Synthase Kinase-3 Beta)</th></tr>
<tr><td>Gene</td><td>[GSK3B](/genes/gsk3b)</td></tr>
<tr><td>UniProt ID</td><td>[P49841](https://www.uniprot.org/uniprot/P49841)</td></tr>
<tr><td>PDB</td><td>1PYX, 2OW3, 4J7B, 5HLN</td></tr>
<tr><td>Molecular Weight</td><td>46.7 kDa</td></tr>
<tr><td>Localization</td><td>Cytoplasm, nucleus, mitochondria</td></tr>
<tr><td>Family</td><td>CMGC kinase family, GSK-3 subfamily</td></tr>
<tr><td>Disease</td><td>AD, PD, BD, Diabetes</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

Glycogen synthase kinase-3 beta (GSK-3β) is a serine/threonine kinase originally identified for its role in glycogen metabolism. It has since emerged as a central signaling hub that phosphorylates over 100 substrates, making it one of the most promiscuous kinases in the human proteome. [GSK-3β](/entities/gsk3-beta) is a key [tau](/proteins/tau) kinase in Alzheimer's disease and is implicated in Parkinson's disease, bipolar disorder, and cancer.

Structure

GSK-3β has a typical kinase domain architecture:

• N-terminal domain: Contains inhibitory phosphorylation site (Ser9)
• Kinase domain (residues 35-350): ATP-binding pocket, substrate-binding groove
• Activation loop: Requires priming of substrates
• C-terminal tail: Regulatory interactions

GSK-3β Protein

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2">GSK-3β (Glycogen Synthase Kinase-3 Beta)</th></tr>
<tr><td>Gene</td><td>[GSK3B](/genes/gsk3b)</td></tr>
<tr><td>UniProt ID</td><td>[P49841](https://www.uniprot.org/uniprot/P49841)</td></tr>
<tr><td>PDB</td><td>1PYX, 2OW3, 4J7B, 5HLN</td></tr>
<tr><td>Molecular Weight</td><td>46.7 kDa</td></tr>
<tr><td>Localization</td><td>Cytoplasm, nucleus, mitochondria</td></tr>
<tr><td>Family</td><td>CMGC kinase family, GSK-3 subfamily</td></tr>
<tr><td>Disease</td><td>AD, PD, BD, Diabetes</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

Glycogen synthase kinase-3 beta (GSK-3β) is a serine/threonine kinase originally identified for its role in glycogen metabolism. It has since emerged as a central signaling hub that phosphorylates over 100 substrates, making it one of the most promiscuous kinases in the human proteome. [GSK-3β](/entities/gsk3-beta) is a key [tau](/proteins/tau) kinase in Alzheimer's disease and is implicated in Parkinson's disease, bipolar disorder, and cancer.

Structure

GSK-3β has a typical kinase domain architecture:

• N-terminal domain: Contains inhibitory phosphorylation site (Ser9)
• Kinase domain (residues 35-350): ATP-binding pocket, substrate-binding groove
• Activation loop: Requires priming of substrates
• C-terminal tail: Regulatory interactions

• Ser9 phosphorylation: By AKT, PKA, PKB → Inhibitory, blocks substrate access
• Tyr216 phosphorylation: Autophosphorylation → Activating
• Substrate priming: Most substrates require pre-phosphorylation at +4 position

Normal Function

GSK-3β regulates multiple cellular pathways[@jope2007]:

GSK-3β is constitutively active and inhibited by upstream signals (insulin, growth factors).

Role in Neurodegeneration

Alzheimer's Disease - Tau Phosphorylation

GSK-3β is a major tau kinase, phosphorylating ~40 tau sites[@hanger2009]:

Key tau sites phosphorylated by GSK-3β:

• Ser199, Ser202, Thr205 (AT8 epitope)
• Thr231, Ser235
• Ser396, Ser404 (PHF-1 epitope)
• Ser422

Consequences of tau hyperphosphorylation:

• Impaired microtubule binding
• Tau aggregation into PHFs/NFTs
• Disrupted axonal transport
• Synaptic dysfunction

Additional AD Roles

• [APP](/entities/app-protein) processing: GSK-3β enhances [γ-secretase](/entities/gamma-secretase) activity
• Neuroinflammation: Activates NLRP3 inflammasome via NF-κB
• Synaptic loss: Reduces dendritic spine density
• Mitochondrial dysfunction: Increases mitochondrial fragmentation

Parkinson's Disease

GSK-3β contributes to PD through:

• [α-synuclein](/proteins/alpha-synuclein) phosphorylation: Ser129 phosphorylation promotes aggregation
• Dopaminergic neuron death: GSK-3β activation mediates MPTP toxicity
• Neuroinflammation: Microglial activation via NF-κB[@dill2019]

Bipolar Disorder and Schizophrenia

GSK-3β is a therapeutic target for mood disorders:

• Lithium: Direct and indirect GSK-3β inhibitor (major mechanism)
• Valproate: Indirect inhibition
• Antipsychotics: Some inhibit GSK-3β activity

Therapeutic Targeting

GSK-3β inhibition is a major therapeutic strategy:

| Agent | Mechanism | Status |
|-------|-----------|--------|
| Lithium | Competitive (Mg²⁺), indirect (AKT) | FDA approved (BD) |
| Tideglusib | Irreversible inhibitor | Phase II (AD, PSP - failed) |
| LY2090314 | ATP-competitive | Phase II (cancer) |
| 9-ING-41 | ATP-competitive | Phase I/II (cancer) |
| Kenpaullone | ATP-competitive | Preclinical |

Challenges with GSK-3β inhibitors:

• Broad substrate specificity → toxicity
• Cancer risk (Wnt pathway)
• Metabolic effects
• Cognitive effects of chronic inhibition[@lovestone2010]

See Also

• Tau Protein - Primary GSK-3β substrate
• CDK5 - Another major tau kinase
• AKT - Upstream GSK-3β regulator
• Lithium - GSK-3β inhibitor
• [Tau Hyperphosphorylation](/mechanisms/tau-hyperphosphorylation)

References