ULK4 Protein

ULK4 Protein — Unc-51 Like Kinase 4

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">ULK4 Protein</th></tr> [@autophagy]
<tr><td><strong>Protein Name</strong></td><td>Unc-51 Like Kinase 4</td></tr>
<tr><td><strong>Gene</strong></td><td>[ULK4](/genes/ulk4)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9C0B1](https://www.uniprot.org/uniprot/Q9C0B1)</td></tr>
<tr><td><strong>PDB ID</strong></td><td>Not determined</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>125 kDa</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Cytoplasm, Cytoskeleton</td></tr>
<tr><td><strong>Protein Family</strong></td><td>ULK kinase family</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

ULK4 (Unc-51 Like Kinase 4) is a serine/threonine protein kinase belonging to the ULK family (ULK1-4). While less studied than its siblings ULK1 and ULK2, ULK4 plays crucial roles in neurodevelopment, RNA processing, and has emerged as a protein with relevance to neurodegenerative diseases. [@ulk]

ULK4 is expressed predominantly in the brain, particularly in regions involved in learning and memory such as the [hippocampus](/brain-regions/hippocampus) and [cortex](/brain-regions/cortex). Its unique structure and expression pattern distinguish it from other ULK family members.

Gene and Protein Structure

Gene Information

ULK4 Protein — Unc-51 Like Kinase 4

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">ULK4 Protein</th></tr> [@autophagy]
<tr><td><strong>Protein Name</strong></td><td>Unc-51 Like Kinase 4</td></tr>
<tr><td><strong>Gene</strong></td><td>[ULK4](/genes/ulk4)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9C0B1](https://www.uniprot.org/uniprot/Q9C0B1)</td></tr>
<tr><td><strong>PDB ID</strong></td><td>Not determined</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>125 kDa</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Cytoplasm, Cytoskeleton</td></tr>
<tr><td><strong>Protein Family</strong></td><td>ULK kinase family</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

ULK4 (Unc-51 Like Kinase 4) is a serine/threonine protein kinase belonging to the ULK family (ULK1-4). While less studied than its siblings ULK1 and ULK2, ULK4 plays crucial roles in neurodevelopment, RNA processing, and has emerged as a protein with relevance to neurodegenerative diseases. [@ulk]

ULK4 is expressed predominantly in the brain, particularly in regions involved in learning and memory such as the [hippocampus](/brain-regions/hippocampus) and [cortex](/brain-regions/cortex). Its unique structure and expression pattern distinguish it from other ULK family members.

Gene and Protein Structure

Gene Information

The ULK4 gene is located on chromosome 3p21.2 and encodes a protein of 1,068 amino acids. Unlike ULK1 and ULK2, ULK4 has distinct regulatory features and may have partially redundant but also unique functions.

Protein Domains

ULK4 contains several functional domains: [@structure]

• N-terminal kinase domain: Catalytic serine/threonine kinase activity (~300 aa)
• Intermediate domain: Contains regulatory sequences
• C-terminal domain: Proline-rich region involved in protein-protein interactions
• Unique C-terminal extension: Distinguished feature among ULK family members

Normal Function

ULK4 has distinct functions from other ULK kinases:

Neurogenesis and Brain Development

• Neural progenitor cell proliferation: ULK4 regulates the expansion of neural progenitor cells during development
• Neuronal migration: Involved in proper neuronal migration during corticogenesis
• Axon guidance: Contributes to correct axon pathfinding

RNA Processing

• Alternative splicing: ULK4 controls mRNA processing and alternative splicing events
• Transcriptional regulation: May influence gene expression programs in [neurons](/entities/neurons)

Autophagy Regulation

• Partial [autophagy](/entities/autophagy) function: While ULK4 contributes to autophagy regulation, ULK1 and ULK2 are the primary autophagy initiators
• Stress response: May participate in cellular stress response pathways

Role in Neurodegeneration

Alzheimer's Disease

ULK4 alterations are relevant to AD pathogenesis: [@autophagy]

• Altered expression: ULK4 expression is changed in AD brains, particularly in affected cortical regions
• Autophagy dysfunction: Impaired autophagy is a hallmark of AD, and ULK4 may contribute to this deficit
• Synaptic function: ULK4 variants may affect synaptic maintenance through autophagy-dependent mechanisms

Parkinson's Disease

In PD, ULK4 may play important roles: [@autophagya]

• Autophagy in dopaminergic neurons: ULK4 may affect autophagy in dopaminergic neurons, which are particularly vulnerable in PD
• Protein clearance: ULK4 function could influence the clearance of [alpha-synuclein](/proteins/alpha-synuclein) through autophagy pathways
• Neuroprotection: Reduced ULK4 function may compromise neuronal stress responses

Schizophrenia

ULK4 has been strongly linked to schizophrenia: [@ulka]

• Loss-of-function mutations: ULK4 loss-of-function mutations are associated with increased schizophrenia risk
• Neurodevelopmental hypothesis: ULK4 dysfunction may contribute to neurodevelopmental abnormalities underlying schizophrenia

Neurodevelopmental Disorders

• Rare variants: ULK4 rare variants have been implicated in neurodevelopmental disorders
• Cognitive function: ULK4 may influence cognitive function through its roles in neurogenesis and synaptic plasticity

Therapeutic Implications

Biomarker Potential

• ULK4 expression changes may serve as indicators of neuronal stress
• Genetic variants could inform risk stratification

Drug Target Considerations

• Kinase modulators targeting ULK4 may have therapeutic potential
• Small molecules enhancing ULK4 function could support neuronal survival

See Also

• [ULK1 Protein](/proteins/ulkl1-protein)
• [ULK2 Protein](/proteins/ulkl2-protein)
• [Autophagy Pathway](/mechanisms/autophagy)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Schizophrenia](/diseases/schizophrenia)

References