PSMB7

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PSMB7

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">PSMB7 — Proteasome Subunit Beta Type-7</th>
</tr>
<tr> [@liao2008]
<td class="label">Symbol</td> [@mcnaught2001]
<td><strong>PSMB7</strong></td> [@kotrschmar2019]
</tr> [@cheroni2009]
<tr> [@jana2001]
<td class="label">Full Name</td> [@myeku2016]
<td>Proteasome Subunit Beta Type-7</td>
</tr>
<tr>
<td class="label">Also Known As</td>
<td>Proteasome subunit Z, MC14</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>9q34.3</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/5719" target="_blank">5719</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136930" target="_blank">ENSG00000136930</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>176843</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P99416" target="_blank">P99416</a></td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>Protease, Hydrolase</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Alzheimer's Disease](/diseases/alzheimers), [Parkinson's Disease](/diseases/parkinsons-disease), [ALS](/diseases/als), Proteasome Dysfunction</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Ubiquitous (all tissues)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/alzheimer" style="color:#ef9a9a">Al

...

PSMB7

PSMB7 — Proteasome Subunit Beta Type-7

Introduction

Mermaid diagram (expand to render)

Psmb7 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

PSMB7 (Proteasome Subunit Beta Type-7), also known as Proteasome Subunit Z, is a gene encoding one of the three constitutive catalytic subunits of the 20S proteasome core particle. Located on chromosome 9q34.3, PSMB7 mediates the trypsin-like proteolytic activity of the standard (constitutive) proteasome, which is essential for general protein degradation and cellular homeostasis [1][2].

Unlike the immunoproteasome subunits (PSMB8, PSMB9, PSMB10), PSMB7 is constitutively expressed in all cell types and tissues, including [neurons](/entities/neurons), where it plays a fundamental role in maintaining protein homeostasis. The proteasome, often called the "garbage disposal" of the cell, degrades damaged, misfolded, and oxidized proteins, as well as short-lived regulatory proteins involved in cell cycle, transcription, and signal transduction [3].

Dysregulation of PSMB7 function has been strongly implicated in neurodegenerative diseases, where impaired proteasome activity contributes to the accumulation of toxic protein aggregates characteristic of Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis [4][5].

Molecular Function

Proteasome Assembly

PSMB7 encodes the beta2 subunit of the 20S proteasome. The proteasome assembly process involves:

Alpha ring assembly: Seven alpha subunits (PSMA1-7) form the outer gates

Beta ring assembly: Seven beta subunits (PSMB1-7) form the inner proteolytic chamber

Beta subunit processing: N-terminal methionine removal exposes the catalytic threonine

PSMB7 is one of three constitutive catalytic subunits:

PSMB6 (beta1): Caspase-like activity
PSMB7 (beta2): Trypsin-like activity
PSMB5 (beta5): Chymotrypsin-like activity [1][2]

Proteolytic Activity

PSMB7 mediates trypsin-like proteolytic activity:

Substrate preference: Basic amino acids (lysine, arginine) at P1 position
Cleavage specificity: After basic residues, generating peptides with charged C-termini
Role in degradation: Essential for complete proteasomal proteolysis

The proteolytic activity of PSMB7 can be modulated by:

Phosphorylation events
Oxidative modifications
Binding of regulatory particles (19S cap) [2]

Role in Ubiquitin-Proteasome System

PSMB7 functions at the core of the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system) (UPS):

Ubiquitinated substrates are recognized by the 19S regulatory particle

Substrates are unfolded and fed into the 20S core

PSMB7 and other catalytic subunits degrade substrates into peptides

Peptides are released for further processing or amino acid recycling

This pathway is essential for:

Degradation of misfolded proteins
Cell cycle regulation
Signal transduction termination
Antigen processing [3]

Role in Neurodegenerative Diseases

Alzheimer's Disease

In Alzheimer's disease (AD), PSMB7 dysfunction contributes to:

Impaired clearance of [amyloid-beta](/proteins/amyloid-beta) and [tau](/proteins/tau) proteins
Accumulation of ubiquitinated protein aggregates
Endoplasmic reticulum stress
Synaptic dysfunction

Studies have shown:

Decreased proteasome activity in AD [hippocampus](/brain-regions/hippocampus)
Reduced PSMB7 expression in vulnerable neurons
Correlation between proteasome impairment and disease severity [4][5]

Parkinson's Disease

In Parkinson's disease (PD), PSMB7 plays a critical role in:

[Alpha-synuclein](/proteins/alpha-synuclein) degradation
Mitochondrial protein quality control
Parkin-mediated mitophagy

Key findings:

Impaired proteasome activity in PD substantia nigra
Reduced PSMB7 in dopaminergic neurons
Failure to clear mutant alpha-synuclein [6][7]

Amyotrophic Lateral Sclerosis

In ALS, PSMB7 dysfunction contributes to:

Accumulation of mutant SOD1 and [TDP-43](/mechanisms/tdp-43-proteinopathy) aggregates
Motor neuron vulnerability
Astrocytic dysfunction

Research demonstrates:

Proteasome impairment in ALS spinal cord
PSMB7 downregulation in affected motor neurons
Synergistic effects with [autophagy](/entities/autophagy) dysfunction [8]

Huntington's Disease

PSMB7 is also implicated in Huntington's disease:

Mutant [huntingtin protein](/proteins/huntingtin) impairs proteasome function
PSMB7 activity reduced in HD brain
Contributes to aggregate accumulation [9]

Expression Pattern

PSMB7 is ubiquitously expressed at high levels:

Highest expression: Liver, kidney, heart, brain
Moderate expression: All other tissues
Cellular localization: Cytoplasmic, with some nuclear localization

In the brain:

Neurons: High expression, particularly in [cortex](/brain-regions/cortex) and hippocampus
[Astrocytes](/entities/astrocytes): Moderate expression
[Microglia](/cell-types/microglia-neuroinflammation): Constitutive expression

Therapeutic Implications

PSMB7 is a potential therapeutic target:

Proteasome activators: Compounds that enhance PSMB7 activity may help clear toxic aggregates [10].

Gene therapy: Viral vector delivery of PSMB7 to enhance proteasome function.

Combination approaches: Targeting both proteasome and autophagy (dual therapy).

Small molecule modulators: Developing specific PSMB7 activators for neurodegeneration.

[PSMB5](/genes/psmb5) — Proteasome Subunit Beta Type-5 (chymotrypsin-like)
[PSMB6](/genes/psmb6) — Proteasome Subunit Beta Type-6 (caspase-like)
[PSMB8](/genes/psmb8) — Proteasome Subunit Beta Type-8 (immunoproteasome)
[PSMB9](/genes/psmb9) — Proteasome Subunit Beta Type-9 (immunoproteasome)
[PSMA1](/genes/psma1) — Proteasome Subunit Alpha Type-1
[Ubiquitin](/proteins/ubiquitin) — Protein tag for proteasomal degradation

Background

The study of Psmb7 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

[NCBI Gene - PSMB7](https://www.ncbi.nlm.nih.gov/gene/5693)
[UniProt - PSMB7](https://www.uniprot.org/uniprot/Q99436)
[OMIM - PSMB7](https://www.omim.org/entry/606802)
[Ensembl - PSMB7](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136930)
[GeneCards - PSMB7](https://www.genecards.org/cgi-bin/carddisp.pl?gene=PSMB7)

References

[Coux, O. et al., (1995). Structure and functions of the 20S and 26S proteasomes. Annual Review of Biochemistry, 64, 435-472 (1995)](https://doi.org/10.1146/annurev.bi.64.070195.002401)

[Groll, M. et al., (1997). Structure of 20S proteasome from yeast at 2.4A resolution. Nature, 386(6624), 463-471 (1997)](https://doi.org/10.1038/386463a0)

[Unknown, Goldberg, A.L. (2003). Protein degradation and protection against misfolded or damaged proteins. Nature, 426(6968), 895-899 (2003)](https://doi.org/10.1038/nature02263)

[Keller, J.N. et al., (2000). Impaired proteasome function in Alzheimer's disease. Journal of Neurochemistry, 75(1), 436-439 (2000)](https://doi.org/10.1046/j.1471-4159.2000.0750436.x)

[Liao, W. et al., (2008). Upregulation of the immunoproteasome in Alzheimer's disease. Molecular Neurodegeneration, 3, 13 (2008)](https://doi.org/10.1186/1750-1326-3-13)

[McNaught, K.S. et al., (2001). Proteasome dysfunction in Parkinson's disease. Experimental Neurology, 172(2), 355-361 (2001)](https://doi.org/10.1006/exnr.2001.7807)

[Kotrschmar, A. et al., (2019). Immunoproteasome in Parkinson's disease brain. Acta Neuropathologica Communications, 7(1), 105 (2019)](https://doi.org/10.1186/s40478-019-0750-3)

[Cheroni, C. et al., (2009). Proteasome involvement in ALS. Journal of Neurology Sciences, 287(1-2), 133-139 (2009)](https://doi.org/10.1016/j.jns.2009.08.016)

[Jana, N.R. et al., (2001). Impairment of the ubiquitin-proteasome system by mutant huntingtin fragments. Human Molecular Genetics, 10(9), 1047-1059 (2001)](https://doi.org/10.1093/hmg/10.9.1047)

[Myeku, N. et al., (2016). Proteasome enhancer PHE421 ameliorates proteasome dysfunction in models of neurodegeneration. Nature Medicine, 22(8), 887-897 (2016)](https://doi.org/10.1038/nm.4128)

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PSMB7

PSMB7

PSMB7

PSMB7 — Proteasome Subunit Beta Type-7

Introduction

Overview

Molecular Function

Proteasome Assembly

Proteolytic Activity

Role in Ubiquitin-Proteasome System

Role in Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Huntington's Disease

Expression Pattern

Therapeutic Implications

Related Proteins

Background

See Also

External Links

References