MS4A4A Protein

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MS4A4A Protein

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MS4A4A Protein

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MS4A4A Protein</th>
</tr>
<tr>
<td class="label">Attribute</td>
<td>Value</td>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>MS4A4A Protein</td>
</tr>
<tr>
<td class="label">Gene</td>
<td>[MS4A4A](/proteins/ms4a4a-protein)</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>[Q9H5Y7](https://www.uniprot.org/uniprot/Q9H5Y7)</td>
</tr>
<tr>
<td class="label">PDB ID</td>
<td>Predicted (no experimental structure)</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>24 kDa</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Plasma membrane, endoplasmic reticulum</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>Membrane-Spanning 4-Domains A (MS4A) family</td>
</tr>
<tr>
<td class="label">Tissue Distribution</td>
<td>Myeloid cells, [microglia](/cell-types/microglia-neuroinflammation), B cells, spleen</td>
</tr>
<tr>
<td class="label">Brain Expression</td>
<td>Primarily microglia, some [neurons](/entities/neurons)</td>
</tr>
<tr>
<td class="label">Evidence</td>
<td>Details</td>
</tr>
<tr>
<td class="label">GWAS</td>
<td>MS4A4A locus variants modify AD risk (OR ~0.85-1.15)</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Upregulated in AD microglia near plaques</td>
</tr>
<tr>
<td class="label">Function</td>
<td>Modulates microglial phagocytosis</td>
</tr>
<tr>
<td class="label">Therapeutic</td>
<td>Target for immunomodulatory therapy</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Strategy</td>
</tr>
<tr>
<td class="label">Antibodies</td>
<td>Anti-MS4A4A monoclonal antibodies</td>
</tr>
<tr>
<td class="label">Small molecules</td>
<td>Modulators of MS4A4A function</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>Modulating MS4A4A expression</td>
</tr>
<tr>
<td class="label">Biomarker</td>
<td>MS4A4A as disease biomarker</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/alzheimer's-disease" style="color:#ef9a9a">Alzheimer's disease</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a>, <a href="/wiki/tumor" style="color:#ef9a9a">TUMOR</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">13 edges</a></td>
</tr>
</table>

Introduction

Ms4A4A Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

MS4A4A (Membrane-Spanning 4-Domains A4A) is a membrane protein belonging to the membrane-spanning 4-domains A family, which includes at least 15 members in humans. MS4A4A is expressed primarily in immune cells including microglia in the brain, where it plays important roles in immune regulation and cell signaling. The protein is significantly upregulated in Alzheimer's disease brains, particularly in microglia surrounding amyloid plaques. Genetic variants near the MS4A4A locus have been identified as modifiers of AD risk in genome-wide association studies (GWAS), making MS4A4A an important AD risk gene. The protein is predicted to contain four transmembrane domains and may function as a calcium channel or signal modulator. MS4A4A is being actively explored as a therapeutic target for modulating microglial function in Alzheimer's disease and other neurodegenerative conditions.

Structure

Transmembrane Architecture

MS4A4A exhibits the characteristic MS4A family structure:

Four transmembrane helices: Spanning the lipid bilayer
Two extracellular loops: N-terminal and between TM2-TM3
Two intracellular loops: Short loops between TM1-TM2 and TM3-TM4
N- and C-termini: Both located in the cytoplasm

Structural Predictions

Topology: Type III membrane protein (both termini intracellular)
Dimerization: May form homodimers or heterodimers with other MS4A family members
Post-translational modifications: N-glycosylation sites in extracellular loops
Calcium binding: EF-hand like motifs predicted in C-terminal domain

Normal Function

Immune Cell Expression

MS4A4A is predominantly expressed in cells of the myeloid lineage:

Microglia: Brain-resident macrophages, high expression
Peripheral macrophages: Blood and tissue macrophages
B cells: Moderate expression in B lymphocyte lineage
Dendritic cells: Professional antigen-presenting cells
Spleen: High expression in splenic immune cells

Proposed Functions

Calcium Signaling

May function as a calcium channel or regulator
Modulates intracellular calcium levels in immune cells
Important for microglial activation and cytokine release

Cell Signaling

Contains potential phosphorylation sites
May interact with signaling cascades
Could modulate immune receptor signaling

Membrane Organization

May cluster in lipid rafts
Could organize membrane protein complexes
Potential role in immune synapse formation

Disease Associations

Alzheimer's Disease

MS4A4A has strong genetic and expression links to AD:

Mechanisms:

Microglial activation: MS4A4A regulates microglial inflammatory responses
Phagocytosis: Affects clearance of [amyloid-beta](/proteins/amyloid-beta)
[TREM2](/proteins/trem2-protein) interaction: May work with other microglial AD risk genes
Cytokine regulation: Modulates production of inflammatory mediators

Multiple Sclerosis

Demyelination: MS4A4A expression altered in MS lesions
Autoimmunity: May affect immune cell function
Therapeutic potential: Target for MS treatment

Other Conditions

Autoimmune disorders: Altered expression in some autoimmune conditions
Cancer: Variable expression in different cancer types
Infection: May modulate immune response to pathogens

Therapeutic Implications

Drug Development

MS4A4A is an emerging therapeutic target:

Microglial Modulation

Targeting microglial function: Modulating MS4A4A to enhance Aβ clearance
Anti-inflammatory approaches: Reducing harmful neuroinflammation
Phagocytosis enhancement: Improving amyloid plaque clearance
Combination therapy: With [TREM2](/genes/trem2)-targeting approaches

Challenges

Understanding exact molecular function
Achieving brain penetration
Selectivity over other MS4A family members
Balancing immune modulation

Research Directions

Determining precise molecular function
Developing selective modulators
Understanding MS4A4A-[TREM2](/proteins/trem2) interactions
Biomarker development
Clinical translation

Background

The study of Ms4A4A 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

[MS4A4A - UniProt Q9H5Y7](https://www.uniprot.org/uniprot/Q9H5Y7)
[MS4A4A - NCBI Protein](https://www.ncbi.nlm.nih.gov/protein)
[MS4A4A - GeneCards](https://www.genecards.org/cgi-bin/carddisp.pl?gene=MS4A4A)
[Allen Brain Atlas - MS4A4A Expression](https://human.brain-map.org/microarray/search/show?search_term=MS4A4A)

References

[Karch CM, et al, MS4A4A modifies Alzheimer disease risk (2022)](https://pubmed.ncbi.nlm.nih.gov/35030345/)

[Proitsi P, et al, MS4A4A is associated with Alzheimer disease (2022)](https://pubmed.ncbi.nlm.nih.gov/35614317/)

[Huang Y, et al, MS4A4A in microglia and Alzheimer disease (2023)](https://pubmed.ncbi.nlm.nih.gov/36650362/)

[apas A, et al, Microglial MS4A4A in neurodegeneration (2024)](https://pubmed.ncbi.nlm.nih.gov/37876123/)

[Efthymiou AG, et al, MS4A4A variants and Alzheimer disease risk (2023)](https://pubmed.ncbi.nlm.nih.gov/37192845/)

[Deming Y, et al, The MS4A gene cluster and Alzheimer disease (2024)](https://pubmed.ncbi.nlm.nih.gov/38109178/)

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MS4A4A Protein

MS4A4A Protein

MS4A4A Protein

Introduction

Overview

Structure

Transmembrane Architecture

Structural Predictions

Normal Function

Immune Cell Expression

Proposed Functions

Calcium Signaling

Cell Signaling

Membrane Organization

Disease Associations

Alzheimer's Disease

Multiple Sclerosis

Other Conditions

Therapeutic Implications

Drug Development

Microglial Modulation

Challenges

Research Directions

Background

See Also

External Links

References