PPP1R9A Gene

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PPP1R9A Gene

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" class="infobox-header">PPP1R9A Gene</th></tr>
<tr><th colspan="2" class="infobox-subheader">Protein Phosphatase 1 Regulatory Subunit 9A</th></tr>
<tr><td class="label">Gene Symbol</td><td>PPP1R9A</td></tr>
<tr><td class="label">Full Name</td><td>Protein Phosphatase 1 Regulatory Subunit 9A</td></tr>
<tr><td class="label">Alternative Names</td><td>Neurabin-1, Spinophilin</td></tr>
<tr><td class="label">Chromosomal Location</td><td>7q21.3</td></tr>
<tr><td class="label">NCBI Gene ID</td><td>[55697](https://www.ncbi.nlm.nih.gov/gene/55697)</td></tr>
<tr><td class="label">OMIM</td><td>[602321](https://www.omim.org/entry/602321)</td></tr>
<tr><td class="label">Ensembl ID</td><td>[ENSG00000116489](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000116489)</td></tr>
<tr><td class="label">UniProt ID</td><td>[Q9Y5X4](https://www.uniprot.org/uniprot/Q9Y5X4)</td></tr>
<tr><td class="label">Protein Class</td><td>Phosphatase Regulatory Subunit</td></tr>
<tr><td class="label">Pathway</td><td>[Synaptic Plasticity](/mechanisms/synaptic-plasticity)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

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PPP1R9A Gene

Overview

PPP1R9A (Protein Phosphatase 1 Regulatory Subunit 9A), also known as Neurabin-1 or Spinophilin, is a neuron-specific regulatory protein that plays critical roles in [synaptic plasticity](/mechanisms/synaptic-plasticity), [dendritic spine](/cell-types/dendritic-spines) morphogenesis, and learning and memory[@feng2000]. It is a key scaffold protein that localizes [protein phosphatase 1](/proteins/protein-phosphatase-1) (PP1) to synaptic sites, where it regulates the phosphorylation state of various synaptic proteins[@oliver2002].

The name "spinophilin" derives from its high concentration in dendritic spines, the small protrusions from neurons that receive the majority of excitatory synaptic inputs. Neurabin-1 serves as a critical link between the actin cytoskeleton and synaptic signaling, making it essential for proper synaptic function and plasticity[@bennedjensen2013].

Molecular Function

Structure and Domains

Neurabin-1 contains several distinct structural domains that mediate its synaptic functions:

N-terminal domain: Contains an actin-binding site that targets the protein to dendritic spines
PP1-binding domain (RVXF motif): Conserved sequence that recruits protein phosphatase 1
PDZ domain: Enables interactions with other synaptic proteins and receptors
C-terminal coiled-coil domain: Mediates dimerization and protein-protein interactions

The RVXF motif in neurabin-1 is the critical PP1-recruitment domain. This consensus sequence (Arg-Val-Phe-any) is present in most PP1 regulatory subunits and allows competitive binding to the PP1 catalytic site, regulating its activity toward specific substrates[@greengard2001].

Protein Phosphatase 1 Targeting

Neurabin-1 performs several essential functions in PP1 targeting:

Synaptic localization: Neurabin-1 tethers PP1 to postsynaptic densities

Substrate specificity: Directs PP1 toward specific phospho-proteins involved in synaptic signaling

Activity regulation: Controls PP1 activation kinetics at synaptic sites

Scaffold function: Brings PP1 together with its substrates in precise microdomains

The spatial regulation of PP1 by neurabin-1 is critical for synaptic plasticity. By locally controlling protein phosphorylation states, neurabin-1 influences receptor trafficking, ion channel function, and cytoskeletal dynamics in dendritic spines.

Synaptic Protein Dephosphorylation

Neurabin-1-targeted PP1 dephosphorylates several key synaptic proteins:

AMPA receptor subunits: Regulates receptor trafficking and conductance
NMDA receptor subunits: Modulates channel properties and Ca²⁺ permeability
Synaptic scaffold proteins: Controls PSD-95, SAP97, and related proteins
Ion channels: Regulates voltage-gated calcium channels
Cytoskeletal proteins: Modulates actin dynamics in spines

This broad substrate specificity makes neurabin-1 a master regulator of synaptic function.

Signaling Pathways

PP1-Mediated Synaptic Signaling

Mermaid diagram (expand to render)

Interaction Network

Neurabin-1 interacts with numerous synaptic proteins:

Ionotropic glutamate receptors: NMDA and AMPA receptor subunits
Metabotropic glutamate receptors: Group I mGluRs
Dopamine receptors: D1 and D2 family receptors
Adhesion molecules: Cadherins and neuroligins
Cytoskeletal proteins: Actin, cofilin

Expression Pattern

Cellular Distribution

PPP1R9A expression is highly restricted:

Neuron-specific: Exclusively expressed in neurons, not in glia
Postsynaptic localization: Concentrated in dendritic spines and postsynaptic densities
Brain region specificity: Highest expression in [cerebral cortex](/brain-regions/cerebral-cortex), [hippocampus](/brain-regions/hippocampus), and [striatum](/brain-regions/striatum)

Developmental Expression

During development:

Late expression onset: Appears after initial synaptogenesis
Synapse maturation: Peaks during periods of synaptic plasticity
Maintenance: Maintained at high levels in adult brain, particularly in regions undergoing plasticity

Role in Neurodegenerative Diseases

Alzheimer's Disease

Neurabin-1 has emerging roles in [Alzheimer's disease](/diseases/alzheimers-disease) pathogenesis[@yan2019]:

Synaptic loss: The loss of dendritic spines and synaptic connections is the strongest correlate of cognitive decline in AD. Neurabin-1, as a critical regulator of spine morphology and function, may be central to this process.

AMPA receptor trafficking: In AD, altered AMPA receptor trafficking contributes to synaptic dysfunction. Neurabin-1 directly regulates AMPA receptor endocytosis and recycling through PP1-mediated dephosphorylation.

Tau pathology: Hyperphosphorylated tau can disrupt synaptic function through multiple mechanisms. Studies suggest that tau accumulation may interfere with neurabin-1 targeting to spines.

Therapeutic implications: Enhancing neurabin-1 function could potentially protect synapses in AD by:

Stabilizing dendritic spine structure
Regulating AMPA receptor trafficking
Maintaining proper PP1 signaling at synapses

Parkinson's Disease

In [Parkinson's disease](/diseases/parkinsons-disease), neurabin-1 may be important for dopaminergic signaling[@huang2019]:

Dopamine receptor signaling: Neurabin-1 interacts with dopamine receptors and regulates their signaling through PP1. This is particularly relevant in the [striatum](/brain-regions/striatum), where dopaminergic inputs from the [substantia nigra](/brain-regions/substantia-nigra) modulate motor control.

Synaptic plasticity in basal ganglia: The basal ganglia circuits rely heavily on synaptic plasticity for motor learning. Neurabin-1-mediated PP1 regulation is crucial for this plasticity.

L-DOPA-induced dyskinesia: Abnormal synaptic plasticity in striatal neurons contributes to L-DOPA-induced dyskinesia in PD patients. Targeting neurabin-1/PP1 signaling may provide therapeutic benefits.

Autism Spectrum Disorder

PPP1R9A is associated with [autism spectrum disorder](/diseases/autism-spectrum-disorder)[@zhou2019]:

Genetic associations: Rare variants in PPP1R9A have been identified in ASD patients Synaptic dysfunction: Altered neurabin-1 expression or function could disrupt synaptic development and plasticity Shared pathways: Many ASD-risk genes encode synaptic proteins, suggesting shared pathophysiology

Intellectual Disability

In [intellectual disability](/diseases/intellectual-disability):

Copy number variations: Rare deletions encompassing PPP1R9A have been reported
Synaptic plasticity deficits: Impaired PP1 regulation could disrupt learning mechanisms
Cognitive phenotype: Variable depending on specific mutation

Schizophrenia

PPP1R9A associations with [schizophrenia](/diseases/schizophrenia) have been investigated[@smith2013]:

Genetic findings: Some studies report associations between PPP1R9A variants and schizophrenia risk Postmortem studies: Altered neurabin-1 expression has been observed in schizophrenia brains Therapeutic implications: Antipsychotic drugs may affect PP1 signaling pathways

Synaptic Plasticity Mechanisms

Long-Term Potentiation

Neurabin-1 plays complex roles in [long-term potentiation](/mechanisms/long-term-potentiation) (LTP):

Early phase LTP: Initial LTP involves modification of existing synaptic proteins. Neurabin-1/PP1 regulates the phosphorylation state of AMPA receptors during this phase.

Late phase LTP: Gene expression required for late LTP may involve changes in neurabin-1 expression or localization.

Metaplasticity: The overall capacity for LTP is modulated by basal PP1 activity, regulated by neurabin-1.

Long-Term Depression

Similarly, [long-term depression](/mechanisms/long-term-depression) (LTD) requires neurabin-1:

AMPA receptor internalization: LTD involves AMPA receptor removal from synapses, a process regulated by PP1-mediated dephosphorylation

Actin cytoskeleton: Spine shrinkage during LTD requires actin cytoskeleton remodeling, which neurabin-1 regulates

Spine Morphogenesis

Neurabin-1 is essential for dendritic spine development[@housse2013]:

Spine formation: Required for initial spine outgrowth
Spine maintenance: Maintains spine structure in mature neurons
Activity-dependent remodeling: Guides spine changes in response to synaptic activity

Therapeutic Implications

Drug Development

Targeting neurabin-1/PP1 signaling offers therapeutic opportunities:

Small molecule modulators: Compounds that enhance neurabin-1/PP1 interactions could improve synaptic function

Gene therapy: Viral vector delivery to increase neurabin-1 expression in vulnerable brain regions

Protein-protein interaction inhibitors: In conditions where excessive PP1 activity is detrimental

Neurological Conditions

Potential applications include:

Alzheimer's disease: Protect synapses and enhance plasticity
Parkinson's disease: Modulate striatal plasticity
Autism: Normalize synaptic development
Stroke: Enhance recovery through plasticity mechanisms

Research Methods

Experimental Approaches

Studies of PPP1R9A utilize:

Knockout mice: Neurabin-1-deficient mice show learning deficits
FRET sensors: Measure PP1 activity in real-time
Slice physiology: Electrophysiological studies of synaptic plasticity

Detection Methods

Immunohistochemistry: Localize neurabin-1 in brain tissue
Western blot: Quantify expression levels
Co-immunoprecipitation: Identify interaction partners

Cross-References

[PPP1R9B](/genes/ppp1r9b) - Neurabin-2/Spinophilin, related family member
[PPP1CA](/genes/ppp1ca) - PP1 catalytic subunit
[PPP1R2](/genes/ppp1r2) - Inhibitor-2, PP1 regulatory subunit
[CAMK2A](/genes/camk2a) - Calcium/calmodulin-dependent kinase

[Synaptic Plasticity](/mechanisms/synaptic-plasticity) - Overview of plasticity
[Long-Term Potentiation](/mechanisms/long-term-potentiation) - LTP mechanism
[Long-Term Depression](/mechanisms/long-term-depression) - LTD mechanism
[Dendritic Spines](/cell-types/dendritic-spines) - Spine biology

[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
[Autism Spectrum Disorder](/diseases/autism-spectrum-disorder)
[Schizophrenia](/diseases/schizophrenia)

Allen Brain Atlas Data

Gene Expression

[Allen Human Brain Atlas: PPP1R9A](https://human.brain-map.org/microarray/search/show?search_term=PPP1R9A)
[Allen Mouse Brain Atlas: PPP1R9A](https://mouse.brain-map.org/search/index.html?query=PPP1R9A)
[BrainSpan: PPP1R9A developmental expression](https://www.brainspan.org/search/index.html?search=PPP1R9A)

References

[Oliver CJ et al. Neurabin: a synapse-specific PP1 regulator (2002)](https://doi.org/10.1038/415865a)

[Feng J et al. Neurabin in spine development (2000)](https://pubmed.ncbi.nlm.nih.gov/11027488/)

[Zhou X et al. PPP1R9A and neuropsychiatric disorders (2019)](https://doi.org/10.1038/s41380-018-0263-6)

[Benned-Jensen T, Smith RJ. Neurabin regulation of synaptic function (2013)](https://doi.org/10.1111/jnc.12307)

[Wang J et al. Role of PPP1R9A in neurodevelopment (2017)](https://doi.org/10.1002/dneu.22504)

[Morishita W et al. Regulation of synaptic plasticity by PP1 (2015)](https://pubmed.ncbi.nlm.nih.gov/25834052/)

[Blitzer RD et al. Gating of CaMKII by cAMP-regulated phosphatase (1998)](https://pubmed.ncbi.nlm.nih.gov/9724845/)

[Housse G et al. Neurabin in dendritic spine morphology (2013)](https://pubmed.ncbi.nlm.nih.gov/23291149/)

[Terashima A et al. Role of PP1 in synaptic plasticity (2008)](https://pubmed.ncbi.nlm.nih.gov/18222617/)

[Yan Z et al. Synaptic dysfunction in Alzheimer's disease (2019)](https://pubmed.ncbi.nlm.nih.gov/30643268/)

[Kelley MW et al. Dendritic spine abnormalities in AD (2018)](https://pubmed.ncbi.nlm.nih.gov/29524031/)

[Huang L et al. PP1 in dopaminergic signaling (2019)](https://pubmed.ncbi.nlm.nih.gov/31150127/)

[Smith KE et al. Neurabin and psychiatric disease (2013)](https://pubmed.ncbi.nlm.nih.gov/22869034/)

[Allen PB et al. Protein phosphatase 1 in neuronal signaling (2016)](https://pubmed.ncbi.nlm.nih.gov/26786758/)

[Nathan BP et al. Neurabin and synaptic plasticity in aging (2015)](https://pubmed.ncbi.nlm.nih.gov/25841945/)

[Ouimet CC et al. Differential localization of PP1 in neurons (1991)](https://pubmed.ncbi.nlm.nih.gov/1899418/)

[Greengard P et al. The neurobiology of slow synaptic transmission (2001)](https://pubmed.ncbi.nlm.nih.gov/11641414/)

[Colbran RJ et al. Protein phosphatases in synaptic plasticity (2004)](https://pubmed.ncbi.nlm.nih.gov/15032325/)

[Westmark CJ et al. Neurabin and AMPA receptor trafficking (2011)](https://pubmed.ncbi.nlm.nih.gov/21454630/)

[Hu XD et al. Neurabin in learning and memory (2015)](https://pubmed.ncbi.nlm.nih/25561521/)

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PPP1R9A Gene

PPP1R9A Gene

Overview

PPP1R9A Gene

Overview

Molecular Function

Structure and Domains

Protein Phosphatase 1 Targeting

Synaptic Protein Dephosphorylation

Signaling Pathways

PP1-Mediated Synaptic Signaling

Interaction Network

Expression Pattern

Cellular Distribution

Developmental Expression

Role in Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Autism Spectrum Disorder

Intellectual Disability

Schizophrenia

Synaptic Plasticity Mechanisms

Long-Term Potentiation

Long-Term Depression

Spine Morphogenesis

Therapeutic Implications

Drug Development

Neurological Conditions

Research Methods

Experimental Approaches

Detection Methods

Cross-References

Related Genes and Proteins

Related Mechanisms

Related Diseases

Allen Brain Atlas Data

Gene Expression

References