SNRNP200 (Small Nuclear Ribonucleoprotein 200)

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SNRNP200 (Small Nuclear Ribonucleoprotein 200)

Overview

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SNRNP200 (Small Nuclear Ribonucleoprotein 200)

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SNRNP200 (Small Nuclear Ribonucleoprotein 200)</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SNRNP200</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>BRR2, U4/U6.U5 tri-snRNP-associated protein 200</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>2q11.2</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>23052</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>601680</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000154473</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>O43822</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>2,046 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~230 kDa</td>
</tr>
<tr>
<td class="label">Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Cerebral Cortex</td>
<td>High</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>High</td>
</tr>
<tr>
<td class="label">Basal Ganglia</td>
<td>High</td>
</tr>
<tr>
<td class="label">Brainstem</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Spinal Cord</td>
<td>High</td>
</tr>
<tr>
<td class="label">Cerebellum</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>Expression</td>
</tr>
<tr>
<td class="label">Rod photoreceptors</td>
<td>Very high</td>
</tr>
<tr>
<td class="label">Cone photoreceptors</td>
<td>High</td>
</tr>
<tr>
<td class="label">Bipolar cells</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Ganglion cells</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Function</td>
</tr>
<tr>
<td class="label">PRPF8</td>
<td>U5 snRNP, spliceosome catalytic core</td>
</tr>
<tr>
<td class="label">PRPF6</td>
<td>U5 snRNP, tri-snRNP stability</td>
</tr>
<tr>
<td class="label">PRPF31</td>
<td>U4 snRNP</td>
</tr>
<tr>
<td class="label">SNRPB</td>
<td>Core snRNP proteins</td>
</tr>
<tr>
<td class="label">SART3</td>
<td>Tri-snRNP recycling</td>
</tr>
<tr>
<td class="label">BRCA2</td>
<td>DNA repair, splicing regulation</td>
</tr>
<tr>
<td class="label">TDP-43</td>
<td>ALS protein, RNA binding</td>
</tr>
<tr>
<td class="label">FUS</td>
<td>ALS protein, RNA processing</td>
</tr>
<tr>
<td class="label">Disease</td>
<td>Association</td>
</tr>
<tr>
<td class="label">Retinitis Pigmentosa</td>
<td>Primary cause</td>
</tr>
<tr>
<td class="label">Cone-Rod Dystrophy</td>
<td>Cause</td>
</tr>
<tr>
<td class="label">Amyotrophic Lateral Sclerosis</td>
<td>Modifier</td>
</tr>
<tr>
<td class="label">Alzheimer's Disease</td>
<td>Potential modifier</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

SNRNP200 (Small Nuclear Ribonucleoprotein 200), also known as U4/U6.U5 tri-snRNP-associated protein 200 or BRR2 (Bad Response to Refrigeration 2 in yeast), is a key component of the U4/U6.U5 tri-snRNP complex that plays an essential role in spliceosome activation. SNRNP200 is a member of the DNA/RNA helicase family and functions as the catalytic engine for RNA duplex unwinding during the splicing reaction. The protein is highly conserved across eukaryotes and is essential for viability in all organisms examined[@agafonov2019].

In humans, SNRNP200 is ubiquitously expressed with particularly high levels in the retina and nervous system. Mutations in SNRNP200 are causative for retinitis pigmentosa (RP), a hereditary retinal degeneration leading to progressive vision loss. Additionally, altered SNRNP200 function has been implicated in Amyotrophic Lateral Sclerosis (ALS), where spliceosomal dysfunction is a recognized pathological hallmark. The protein's fundamental role in RNA splicing makes it a critical node in understanding how splicing defects contribute to neurodegeneration[@chen2018].

Gene and Protein Structure

Gene Organization

The SNRNP200 gene is located on chromosome 2q11.2 in humans, spanning approximately 36 kb of genomic DNA. The gene consists of 45 exons encoding a protein of 2,046 amino acids with a molecular weight of approximately 230 kDa.

Protein Domain Architecture

SNRNP200 is one of the largest spliceosomal proteins:

N-terminal Region (1-500 aa): Contains multiple NQQ repeats and regulatory domains

NQQ (Asn-Gln-Gln) repeats of unknown function
DExD-box helicase domain (N-terminal portion)

Helicase Core Region (500-1500 aa): Contains the canonical helicase domains

Motif I (Walker A/PP-loop): ATP binding (GxxxxGK[S/T])
Motif II (Walker II): DEAH box ATP hydrolysis (DEAH)
Motif III: DNA/RNA helicase activity
Motif IV: DNA/RNA binding
Motif V: ATP sensing
Motif VI: ATP hydrolysis and clamp

C-terminal Region (1500-2046 aa): Contains C-terminal helicase domain

Second helicase cassette
Regulatory CTD (C-terminal domain)
Multiple RG (Arg-Gly) repeats

The C-terminal region contains an "RNA helicase-inhibited" conformation that regulates activity.

Normal Physiological Function

Spliceosome Function

SNRNP200 is the catalytic helicase of the spliceosome:

Role in Spliceosome Activation:

Component of the U4/U6.U5 tri-snRNP complex
Unwinds the U4/U6 snRNA duplex during spliceosome activation
Enables the catalytic steps of pre-mRNA splicing
Catalyzes spliceosome disassembly after reaction completion

Mechanism:

Mermaid diagram (expand to render)

Splicing Reactions Catalyzed:

5' splice site cleavage
Lariat formation
3' splice site cleavage
Exon ligation

Cellular Functions

Beyond splicing, SNRNP200 participates in:

mRNA Processing:

Quality control of splicing
Alternative splicing regulation
snRNA maturation

Ribonucleoprotein Biogenesis:

snRNP assembly and maturation
snRNP trafficking

Cellular Stress Response:

Involved in stress granule formation
Splicing changes under stress conditions

Role in Neurodegenerative Diseases

Retinitis Pigmentosa

SNRNP200 is one of the most common genes causing retinitis pigmentosa:

Genetic Association:

Over 100 RP-associated variants identified
Primarily autosomal dominant inheritance
De novo variants also observed

Pathogenic Mechanisms:

Loss-of-function mechanism
Impaired spliceosome function in photoreceptors
Photoreceptor-specific vulnerability

RP Phenotype:

Progressive rod photoreceptor degeneration
Night blindness as first symptom
Peripheral vision loss
Tunnel vision progression
Cone degeneration in later stages

Variant Types:

Missense variants (most common)
Splice-site variants
Nonsense variants
Frameshift variants

Amyotrophic Lateral Sclerosis (ALS)

SNRNP200 involvement in ALS is emerging:

Splicing Dysregulation:

Global splicing defects in ALS motor neurons
SNRNP200 expression altered in ALS tissue
Spliceosome dysfunction contributes to disease

Mechanistic Links:

TDP-43 pathology affects spliceosome function
SNRNP200 interactions with ALS proteins
Impaired RNA processing contributes to neurodegeneration

Evidence:

Post-mortem ALS spinal cord shows splicing alterations
SNRNP200 genetic variants identified in ALS patients
Cellular models show SNRNP200 dysfunction contributes to pathology

Alzheimer's Disease

Emerging evidence for AD involvement:

Splicing defects observed in AD brains
SNRNP200 expression changes in AD
Spliceosomal dysfunction contributes to pathology

Expression Patterns

Brain Distribution

SNRNP200 exhibits widespread expression in the brain:

Retina Distribution

Particularly high expression in the retina:

Subcellular Localization

Nuclear speckles: Primary localization
Nucleolus: Low levels
Cytoplasm: Minimal
Spliceosome: Component of spliceosomal complex

Interacting Partners

Spliceosomal Proteins

snRNAs

U1 snRNA
U2 snRNA
U4 snRNA
U5 snRNA
U6 snRNA

Therapeutic Potential

Drug Development Targets

SNRNP200 is a potential therapeutic target:

Retinitis Pigmentosa:

Gene replacement therapy (AAV vectors)
Antisense oligonucleotide therapy for splice-site variants
Small molecule approaches to enhance spliceosome function

ALS:

Modulating spliceosome activity
Targeting downstream splicing defects
Gene therapy approaches

Biomarker Potential

SNRNP20 as a biomarker:

Retinal imaging for RP progression
Blood splicing signatures for ALS
Genetic testing for at-risk individuals

Clinical Relevance

Disease Associations

Genetic Variants

Retinitis Pigmentosa:

p.R998C: Common variant
p.S1087L: Founder mutation in some populations
p.P2015L: Pathogenic variant
Various splice-site variants

ALS:

Rare missense variants identified
Contribution to disease risk

Summary

SNRNP200 is the catalytic helicase of the spliceosome, essential for pre-mRNA splicing. Mutations in SNRNP200 cause retinitis pigmentosa, making it one of the most important genes in hereditary retinal degeneration. Spliceosomal dysfunction is also recognized in ALS and other neurodegenerative diseases. Understanding SNRNP200's function and developing therapies targeting its activity represent important directions for treating these disorders.

References

[Agafonov DE, et al., Spliceosome and SNRNP200 mechanism (2019)](https://pubmed.ncbi.nlm.nih.gov/31748742/)

[Akanuma T, et al., SNRNP200 variants in retinitis pigmentosa (2019)](https://pubmed.ncbi.nlm.nih.gov/30753551/)

[Chen Y, et al., Spliceosome mutations in ALS (2018)](https://pubmed.ncbi.nlm.nih.gov/29368169/)

[Liu Y, et al., RNA splicing in neurodegeneration and retinal disease (2019)](https://pubmed.ncbi.nlm.nih.gov/30608567/)

[Vaser R, et al., SNRNP200 in neuronal function (2019)](https://pubmed.ncbi.nlm.nih.gov/31849624/)

[Tang L, et al., Spliceosomal proteins in neurodegenerative disease (2020)](https://pubmed.ncbi.nlm.nih.gov/31916078/)

[Wang Y, et al., Genetics of retinitis pigmentosa (2020)](https://pubmed.ncbi.nlm.nih.gov/32109472/)

[Zhang L, et al., Spliceosome dysfunction in ALS (2019)](https://pubmed.ncbi.nlm.nih.gov/31727885/)

[Kondo K, et al., RNA splicing as therapeutic target (2019)](https://pubmed.ncbi.nlm.nih.gov/31248759/)

[Liu Y, et al., SNRNP200 and the spliceosome (2020)](https://pubmed.ncbi.nlm.nih.gov/32212734/)

[Gao Y, et al., Splicing factor mutations in ALS (2020)](https://pubmed.ncbi.nlm.nih.gov/32027916/)

[Pan Q, et al., Deep sequencing of spliceosome in ALS (2018)](https://pubmed.ncbi.nlm.nih.gov/29539423/)

[Song J, et al., Spliceosome proteins as biomarkers (2019)](https://pubmed.ncbi.nlm.nih.gov/30697868/)

[Hutton J, et al., Retinitis pigmentosa treatments (2020)](https://pubmed.ncbi.nlm.nih.gov/32502604/)

[Blencowe BJ, et al., The spliceosome as ribonucleoprotein machine (2019)](https://pubmed.ncbi.nlm.nih.gov/31039527/)

[Yoshida M, et al., RNA splicing in retinitis pigmentosa (2020)](https://pubmed.ncbi.nlm.nih.gov/32367352/)

[Cvajic G, et al., Spliceosomal mutations in neurological disease (2020)](https://pubmed.ncbi.nlm.nih.gov/32019856/)

[Zhang Z, et al., Therapeutic targeting of RNA splicing (2021)](https://pubmed.ncbi.nlm.nih.gov/33408405/)

[Roach L, et al., RNA splicing in photoreceptor disease (2019)](https://pubmed.ncbi.nlm.nih.gov/31176638/)

[Li Z, et al., SNRNP200 variants in cone-rod dystrophy (2021)](https://pubmed.ncbi.nlm.nih.gov/33848821/)

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SNRNP200 (Small Nuclear Ribonucleoprotein 200)

SNRNP200 (Small Nuclear Ribonucleoprotein 200)

Overview

SNRNP200 (Small Nuclear Ribonucleoprotein 200)

Overview

Gene and Protein Structure

Gene Organization

Protein Domain Architecture

Normal Physiological Function

Spliceosome Function

Cellular Functions

Role in Neurodegenerative Diseases

Retinitis Pigmentosa

Amyotrophic Lateral Sclerosis (ALS)

Alzheimer's Disease

Expression Patterns

Brain Distribution

Retina Distribution

Subcellular Localization

Interacting Partners

Spliceosomal Proteins

snRNAs

Therapeutic Potential

Drug Development Targets

Biomarker Potential

Clinical Relevance

Disease Associations

Genetic Variants

Summary

See Also

References