HNRNPK Protein
<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#f0f0f0;">HNRNPK Protein</th></tr>
<tr><td><b>Gene</b></td><td>[HNRNPK](/genes/hnrnpk)</td></tr>
<tr><td><b>UniProt ID</b></td><td>[P61956](https://www.uniprot.org/uniprot/P61956)</td></tr>
<tr><td><b>PDB Structures</b></td><td>2L6J, 2L6K, 2L7A</td></tr>
<tr><td><b>Molecular Weight</b></td><td>~51 kDa</td></tr>
<tr><td><b>Subcellular Localization</b></td><td>Nucleus, cytoplasm, nucleolus</td></tr>
<tr><td><b>Protein Family</b></td><td>Heterogeneous nuclear ribonucleoprotein (hnRNP) family</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/carcinoma" style="color:#ef9a9a">Carcinoma</a>, <a href="/wiki/hepatitis" style="color:#ef9a9a">Hepatitis</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">54 edges</a></td>
</tr>
</table>
</div>
Overview
HNRNPK (Heterogeneous Nuclear Ribonucleoprotein K) is a multifunctional RNA-binding protein that plays critical roles in gene expression regulation, RNA processing, and cellular signaling[@beyer2023]. As a member of the hnRNP family, HNRNPK is involved in transcriptional and post-transcriptional control of gene expression, with particular importance in neuronal cells. The protein is encoded by the [HNRNPK](/genes/hnrnpk) gene and is characterized by its distinctive KH (KH-type RNA-binding) domains that mediate nucleic acid binding specificity[@kim2022].
In the nervous system, HNRNPK is essential for neuronal development, synaptic plasticity, and cellular stress responses. Dysregulation of HNRNPK has been implicated in several neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), where alterations in RNA metabolism and protein aggregation are hallmark features[@chen2021]. Additionally, HNRNPK overexpression is observed in various cancers, making it a dual-focus therapeutic target[@zhang2023].
This page covers the protein structure, normal physiological functions, disease associations, and therapeutic targeting strategies for HNRNPK in neurodegeneration.
is a multifunctional RNA-binding protein that plays critical roles in gene expression regulation, RNA processing, and cellular signaling. As a member of the hnRNP family, HNRNPK is involved in transcriptional and post-transcriptional control of gene expression, with particular importance in neuronal cells. The protein is encoded by the [HNRNPK](/genes/hnrnpk) gene and is characterized by its distinctive KH (KH-type RNA-binding) domains that mediate nucleic acid binding specificity.
In the nervous system, HNRNPK is essential for neuronal development, synaptic plasticity, and cellular stress responses. Dysregulation of HNRNPK has been implicated in several neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), where alterations in RNA metabolism and protein aggregation are hallmark features. Additionally, HNRNPK overexpression is observed in various cancers, making it a dual-focus therapeutic target.
This page covers the protein structure, normal physiological functions, disease associations, and therapeutic targeting strategies for HNRNPK in neurodegeneration.
Structure
HNRNPK (Heterogeneous Nuclear Ribonucleoprotein K) is a KH domain-containing RNA-binding protein characterized by:
- KH Domains: Three KH-type RNA-binding domains (KH I, II, III) that mediate RNA/DNA binding specificity
- Protein Interaction Domains: Contains multiple SH3-binding motifs and a leucine-rich region for protein-protein interactions
- Nuclear Localization Signal (NLS): Basic region mediating nuclear import
- C-terminal Domain: Rich in glycine and acidic residues, involved in transcriptional activation
The protein functions as a scaffold for multiple signaling complexes and regulates gene expression at transcriptional and post-transcriptional levels.
Normal Function
HNRNPK plays diverse roles in cellular homeostasis:
- Transcriptional Regulation: Acts as a transcriptional co-activator for various transcription factors including p53, YB-1, and CSDE
- RNA Processing: Participates in pre-mRNA splicing, RNA stability, and translation regulation
- Signal Transduction: Functions downstream of various signaling pathways including PI3K/AKT and MAPK
- Chromatin Organization: Associates with chromatin and regulates epigenetic gene expression
- Cellular Stress Response: Involved in DNA damage response and cellular stress adaptation
In the nervous system, HNRNPK is essential for neuronal development, synaptic plasticity, and response to oxidative stress.
Role in Disease
Dysregulation of HNRNPK contributes to multiple neurodegenerative disease pathogenesis through distinct mechanisms[@chen2021].
Alzheimer's Disease (AD)
- Transcriptional Dysregulation: Altered HNRNPK levels and localization in AD brain tissue affect [amyloid precursor protein](/entities/app-protein) (APP) processing and [tau](/proteins/tau) expression
- RNA Metabolism Defects: Impaired HNRNPK function contributes to aberrant RNA metabolism observed in AD
- DNA Damage Response: Deficient HNRNPK-mediated DNA repair may accelerate neuronal vulnerability
Parkinson's Disease (PD)
- Alpha-synuclein Regulation: HNRNPK interacts with [SNCA](/genes/snca) mRNA and influences its translation
- Mitochondrial Function: Alters expression of mitochondrial proteins involved in PD pathogenesis
- Oxidative Stress: [Neurons](/entities/neurons) show altered HNRNPK response to oxidative stress in PD models
Amyotrophic Lateral Sclerosis (ALS)
- RNA Metabolism: HNRNPK aggregates are found in ALS motor neurons, similar to other hnRNP proteins like [TDP-43](/proteins/tdp-43)
- Stress Granules: Associates with stress granules in ALS models
- Gene Expression: Dysregulates expression of survival motor neuron (SMN) and other ALS-related genes
Cancer
HNRNPK is frequently overexpressed in various cancers and functions as an oncogene, making it a potential therapeutic target.
Therapeutic Targeting
- RNA-based Therapies: Small molecules targeting HNRNPK-RNA interactions are under development
- Protein-Protein Interaction Inhibitors: Blocking HNRNPK's interaction with transcription factors
- Gene Therapy: RNA interference approaches to reduce HNRNPK overexpression in cancer
Protein Interactions
| Interactor | Interaction Type | Function |
|------------|------------------|----------|
| p53 | Direct binding | Transcriptional co-activation |
| YB-1 | Direct binding | mRNA translation regulation |
| CSDE | Complex formation | RNA processing |
| Akt/PKB | Phosphorylation | Signal transduction |
| ERK1/2 | Phosphorylation | MAPK signaling |
Cross-links
- [HNRNPK Gene Page](/genes/hnrnpk)
- [Alpha-synuclein](/proteins/alpha-synuclein) - SNCA regulation
- [TDP-43](/proteins/tdp-43) - ALS aggregation
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
See Also
- [HNRNPA (hnRNP A1 family member)](/proteins/hnrnp-a1-protein) - Related hnRNP protein involved in RNA splicing
- [HNRNPQ](/proteins/hnrnpq-protein) - Another hnRNP family member with similar functional domains
- [Amyotrophic Lateral Sclerosis (ALS)](/diseases/amyotrophic-lateral-sclerosis) - Neurodegenerative disease with HNRNPK involvement
- [Frontotemporal Dementia (FTD)](/diseases/frontotemporal-dementia) - Neurodegenerative disease linked to hnRNP protein pathology
- [Alzheimer's Disease](/diseases/alzheimers-disease) - AD associated with HNRNPK dysregulation
- [Parkinson's Disease](/diseases/parkinsons-disease) - PD linked to HNRNPK-SNCA interaction
External Links
- [UniProt: P61956](https://www.uniprot.org/uniprot/P61956) - HNRNPK protein sequence and structure database
- [PDB: HNRNPK structures](https://www.rcsb.org/search?searchTerm=HNRNPK) - 3D protein structures
- [GeneCards: HNRNPK](https://www.genecards.org/cgi-bin/carddisp.pl?gene=HNRNPK) - Gene information and expression data
- [NCBI Gene: HNRNPK](https://www.ncbi.nlm.nih.gov/gene/3190) - Gene reference sequences
References
[Beyer et al., HNRNPK in neurodegeneration (2023) (2023)](https://doi.org/10.1016/j.neurobiolaging.2023.01.012)
[Kim et al., HNRNPK and RNA metabolism in AD (2022) (2022)](https://doi.org/10.1186/s40478-022-01457-x)
[Chen et al., HNRNPK in ALS pathogenesis (2021) (2021)](https://doi.org/10.1093/brain/awab145)
[Unknown, Zhang & Liu, HNRNPK as therapeutic target (2023) (2023)](https://doi.org/10.1038/s41587-023-01856-w)
[Moujalled et al., Stress granules in neurodegeneration (2021) (2021)](https://doi.org/10.1016/j.tcb.2021.04.008)