PPP3CB Protein

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PPP3CB Protein

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PPP3CB Protein (Calcineurin B-like Protein)

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">PPP3CB Protein</th>
</tr>
<tr>
<td class="label">Gene</td>
<td>[PPP3CB](/genes/ppp3cb)</td>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>Calcineurin A subunit beta</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>[P16234](https://www.uniprot.org/uniprotkb/P16234)</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~59 kDa</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Cytoplasm, nucleus (upon activation)</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Brain (hippocampus, cortex), testis</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>Ser/Thr protein phosphatase 2B (PP2B)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/amyotrophic-lateral-sclerosis" style="color:#ef9a9a">Amyotrophic Lateral Sclerosis</a>, <a href="/wiki/ataxia" style="color:#ef9a9a">Ataxia</a>, <a href="/wiki/huntington" style="color:#ef9a9a">Huntington</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">145 edges</a></td>
</tr>
</table>

Introduction

...

PPP3CB Protein (Calcineurin B-like Protein)

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">PPP3CB Protein</th>
</tr>
<tr>
<td class="label">Gene</td>
<td>[PPP3CB](/genes/ppp3cb)</td>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>Calcineurin A subunit beta</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>[P16234](https://www.uniprot.org/uniprotkb/P16234)</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~59 kDa</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Cytoplasm, nucleus (upon activation)</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Brain (hippocampus, cortex), testis</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>Ser/Thr protein phosphatase 2B (PP2B)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/amyotrophic-lateral-sclerosis" style="color:#ef9a9a">Amyotrophic Lateral Sclerosis</a>, <a href="/wiki/ataxia" style="color:#ef9a9a">Ataxia</a>, <a href="/wiki/huntington" style="color:#ef9a9a">Huntington</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">145 edges</a></td>
</tr>
</table>

Introduction

PPP3CB encodes the calcineurin B-like protein 1 (also known as CNAβ or PP2B), the catalytic subunit beta isoform of calcineurin, a calcium-dependent serine/threonine phosphatase that plays critical roles in neuronal signal transduction, synaptic plasticity, and gene expression regulation[@klee1998]. Calcineurin is unique among phosphatases for its requirement for both calcium and calmodulin, making it a key decoder of calcium signals in [neurons](/entities/neurons)[@rusnak2000]. Dysregulation of calcineurin signaling has been implicated in Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions[@foster2001].

Overview

PPP3CB is one of three catalytic subunit genes (PPP3CA, PPP3CB, PPP3CC) encoding the calcineurin Aα, [Aβ](/proteins/amyloid-beta), and Aγ isoforms respectively[@klee1998]. The PPP3CB isoform is predominantly expressed in the brain and testis, with particularly high expression in regions involved in learning and memory including the [hippocampus](/brain-regions/hippocampus) and cerebral [cortex](/brain-regions/cortex)[@matsumoto2005]. Calcineurin is unique among protein phosphatases for its high calmodulin affinity and slow calcium dissociation kinetics, allowing it to function as a molecular integrator of calcium signaling patterns[@rusnak2000].

Basic Information

Structure

Catalytic Domain

The calcineurin A subunit contains a catalytic domain in the N-terminal region with the characteristic phosphatase fold[@klee1998]:

Metal-binding site: Two zinc ions and one iron ion coordinated in the active site
Substrate-binding groove: Recognizes specific phosphorylation motifs
Calmodulin-binding domain: Auto-inhibitory region that blocks substrate access in resting state

Regulatory Elements

The protein contains several regulatory features[@rusnak2000]:

Calmodulin-binding domain (CBD): Low-affinity calcium binding domain that activates phosphatase activity
Auto-inhibitory peptide: Blocks active site in resting state, displaced upon calcium/calmodulin binding
Nuclear localization signals (NLS): Target activated calcineurin to the nucleus

Isoform-Specific Features

The PPP3CB isoform contains unique N-terminal sequences that may confer[@matsumoto2005]:

Differential subcellular targeting
Altered calmodulin binding kinetics
Brain-specific regulatory interactions

Function

Calcium-Dependent Phosphatase Activity

Calcineurin dephosphorylates numerous substrate proteins[@rusnak2000]:

NFAT transcription factors: Key target, dephosphorylates NFAT1-4, promoting nuclear translocation
Synaptic proteins: Synapsin I, [NMDA receptor](/entities/nmda-receptor) subunits, AMPA receptor regulatory proteins
Cytoskeletal proteins: [Tau](/proteins/tau), MAP2
Signal transduction molecules: PKC substrates, MAPK pathway components

Synaptic Plasticity

Calcineurin plays a biphasic role in synaptic plasticity[@zhuo1999]:

Long-term depression (LTD): Strong activation of calcineurin required for NMDA receptor-dependent LTD
Memory formation: Negative regulator of memory consolidation in some contexts
Synaptic scaling: Participates in homeostatic synaptic plasticity mechanisms

Gene Expression Regulation

Through NFAT dephosphorylation, calcineurin controls[@rusnak2000]:

Immune response genes in neurons
Synaptic plasticity-related genes
Neuronal survival factors
Developmental gene programs

Role in Neurodegeneration

Alzheimer's Disease

Calcineurin signaling is dysregulated in AD brain[@foster2001][@reddy2018]:

Elevated activity: Paradoxically increased calcineurin activity in AD brain despite calcium dysregulation
NFAT dysregulation: Altered NFAT nuclear localization affects transcription of synaptic genes
Tau dephosphorylation: Calcineurin can dephosphorylate tau at pathological sites
Synaptic dysfunction: Contributes to synaptic loss through altered synaptic protein phosphorylation

Therapeutic Implications

Calcineurin inhibitors have been explored in AD research[@reddy2018]:

FK506 (tacrolimus) shows neuroprotective effects in some AD models
Side effects limit clinical translation
Isoform-selective inhibitors under development

Parkinson's Disease

Calcineurin involvement in PD includes[@bauer2007]:

Dopaminergic neuron survival: Regulates factors important for dopaminergic neuron viability
[Alpha-synuclein](/proteins/alpha-synuclein) toxicity: Modulates pathways affecting alpha-synuclein aggregation
Neuroinflammation: Controls microglial activation states

Amyotrophic Lateral Sclerosis

Calcineurin dysfunction may contribute to ALS through[@floor2002]:

Impaired calcium handling in motor neurons
Altered NFAT signaling affecting glial responses
Dysregulated excitatory amino acid transport

Huntington's Disease

In HD, calcineurin shows[@xifro2013]:

Abnormal interactions with mutant [huntingtin protein](/proteins/huntingtin)
Altered NMDA receptor signaling
Dysregulated gene expression controlling neuronal survival

Therapeutic Targeting

Calcineurin Inhibitors

Clinically used immunosuppressants[@liu1991]:

Cyclosporine A: Binds cyclophilin, inhibits calcineurin
FK506 (Tacrolimus): Binds FKBP12, inhibits calcineurin
Voclosporin: Modified cyclosporine with improved pharmacokinetics

Neuroprotective Strategies

Novel approaches include[@reddy2018]:

Isoform-selective inhibition: Targeting PPP3CB over PPP3CA to reduce immunosuppression
Substrate-selective inhibitors: Blocking specific calcineurin-substrate interactions
[Blood-brain barrier](/entities/blood-brain-barrier) penetrating analogs: Developing CNS-active calcineurin modulators

Interactions and Pathways

Protein Interactions

Calcineurin interacts with numerous proteins[@rusnak2000][@yao2021]:

Calmodulin: Calcium sensor that activates calcineurin
A-kinase anchoring proteins (AKAPs): Target calcineurin to specific subcellular compartments
CABIN1: Large calcineurin-binding protein that inhibits activity
RCAN1 (DSCR1): Endogenous regulator of calcineurin signaling

Signaling Pathways

Calcineurin integrates with multiple signaling pathways[@rusnak2000]:

Calmodulin → Calcineurin → NFAT: Major calcium-signaling axis
NMDA receptor → Calcium → Calcineurin: Synaptic plasticity pathway
mTORC1 ↔ Calcineurin: Cross-talk in synaptic plasticity

Research Tools

Experimental Models

Studying calcineurin in neurodegeneration[@shibasaki1996]:

Knockout mice: PPP3CB null mice show viability but neurological phenotypes
Conditional knockouts: Brain-specific deletion to study neuronal functions
Transgenic models: Overexpression of wild-type and mutant calcineurin

Small Molecule Inhibitors

Cyclosporine A: Classic calcineurin inhibitor
FK506: Potent inhibitor used in transplantation
CAIN: Selective calcineurin inhibitor
AP5: NMDA receptor antagonist (indirectly affects calcineurin activation)

Background

The study of Ppp3Cb Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
[Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
[Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data

References

[Unknown, Klee CB, Ren H, Wang X. Regulation of the calmodulin-stimulated protein phosphatase, calcineurin. Journal of Biological Chemistry. 1998 (1998)](https://doi.org/10.1074/jbc.273.22.13367)

[Unknown, Rusnak F, Mertz P. Calcineurin: form and function. Physiological Reviews. 2000 (2000)](https://doi.org/10.1152/physrev.2000.80.4.1483)

[Foster TC, Sharrow KM, Masse JR, et al., Calcineurin acts upstream of NMDA receptors in the hippocampus to alter synaptic plasticity in memory formation. Neurobiology of Learning and Memory. 2001 (2001)](https://doi.org/10.1006/nlme.2001.3968)

[Matsumoto Y, Abe M, Shinoda C, et al., Expression of calcineurin B subunit isoforms in the central nervous system. Brain Research. 2005 (2005)](https://doi.org/10.1016/j.brainres.2005.03.016)

[Zhuo M, Zhang W, Son H, et al., A calcineurin-mediated long-term depression in the hippocampus. Nature. 1999 (1999)](https://doi.org/10.1038/46353)

[Reddy PH, Yin X, Manczak M, et al., Calcineurin and mitochondrial dysfunction in Alzheimer's disease. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease. 2018 (2018)](https://doi.org/10.1016/j.bbadis.2018.05.015)

[Bauer N, Cutler RG, Cary M, et al., Calcineurin as a therapeutic target in neurodegenerative disease. Neurobiology of Disease. 2007 (2007)](https://doi.org/10.1016/j.nbd.2006.12.014)

[Unknown, Floor E, Wetzel MG. Increased protein oxidation in human substantia nigra pars compacta in comparison with basal ganglia and prefrontal cortex. Journal of Neurochemistry. 2002 (2002)](https://doi.org/10.1046/j.1471-4159.2002.00970.x)

[Xifro X, Giralt A, Saavedra A, et al., Calcineurin involvement in Huntington's disease: implications for transcriptional dysregulation. Journal of Huntington's Disease. 2013 (2013)](https://doi.org/10.3233/JHD-130101)

[Liu J, Farmer JD Jr, Lane WS, et al., Calcineurin is a common target of cyclophilin-cyclosporin A and FKBP12-FK506 complexes. Cell. 1991 (1991)](https://doi.org/10.1016/0092-8674(91)

[Yao YY, Liu Q, Li H, et al., RCAN1 and calcineurin interactions in the cardiovascular system. Frontiers in Cardiovascular Medicine. 2021 (2021)](https://doi.org/10.3389/fcvm.2021.634078)

[Shibasaki F, Price ER, Milan D, et al., Role of kinases and the phosphatase calcineurin in the nuclear shuttling of transcription factor NF-AT4. Nature. 1996 (1996)](https://doi.org/10.1038/382370a0)

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Related Entities

PPP3CBPROTEIN

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wiki_page_id	wp-e21ea7b37835
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📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

50%

Debates

0

Incoming

10

Outgoing

12

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

PPP3CB Protein

PPP3CB Protein (Calcineurin B-like Protein)

Introduction

PPP3CB Protein (Calcineurin B-like Protein)

Introduction

Overview

Basic Information

Structure

Catalytic Domain

Regulatory Elements

Isoform-Specific Features

Function

Calcium-Dependent Phosphatase Activity

Synaptic Plasticity

Gene Expression Regulation

Role in Neurodegeneration

Alzheimer's Disease

Therapeutic Implications

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Huntington's Disease

Therapeutic Targeting

Calcineurin Inhibitors

Neuroprotective Strategies

Interactions and Pathways

Protein Interactions

Signaling Pathways

Research Tools

Experimental Models

Small Molecule Inhibitors

Background

External Links

See Also

References

💬 Discussion