KLK6 Protein

KLK6 Protein

title: KLK6 Protein
<div class="infobox infobox-protein"> [@blaber2002]
<table> [@diamandis2004]
<tr><th>Protein Name</th><td>Kallikrein 6 (Protease M)</td></tr> [@zarghi2018]
<tr><th>Gene</th><td>[KLK6](/genes/klk6)</td></tr> [@okada2010]
<tr><th>UniProt ID</th><td>[Q92815](https://www.uniprot.org/uniprot/Q92815)</td></tr> [@mitsui2019]
<tr><th>PDB Structure</</th><td>1L2E, 2PMN</td></tr>
<tr><th>Molecular Weight</th><td>251 aa (27 kDa)</td></tr>
<tr><th>Subcellular Localization</th><td>Secreted, extracellular</td></tr>
<tr><th>Protein Family</th><td>Trypsin-like serine protease family, Kallikreins</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

KLK6 Protein (Kallikrein 6)

Overview

Klk6 Protein plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Introduction

Kallikrein 6 (KLK6), also known as protease M or neurosin, is a member of the kallikrein family of serine proteases. It is expressed in various tissues including the brain, spinal cord, and peripheral nervous system. KLK6 has been implicated in neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, and multiple system atrophy (MSA), where it plays roles in protein processing, neuroinflammation, and [alpha-synuclein](/mechanisms/alpha-synuclein) metabolism.

Structure

...

KLK6 Protein

title: KLK6 Protein
<div class="infobox infobox-protein"> [@blaber2002]
<table> [@diamandis2004]
<tr><th>Protein Name</th><td>Kallikrein 6 (Protease M)</td></tr> [@zarghi2018]
<tr><th>Gene</th><td>[KLK6](/genes/klk6)</td></tr> [@okada2010]
<tr><th>UniProt ID</th><td>[Q92815](https://www.uniprot.org/uniprot/Q92815)</td></tr> [@mitsui2019]
<tr><th>PDB Structure</</th><td>1L2E, 2PMN</td></tr>
<tr><th>Molecular Weight</th><td>251 aa (27 kDa)</td></tr>
<tr><th>Subcellular Localization</th><td>Secreted, extracellular</td></tr>
<tr><th>Protein Family</th><td>Trypsin-like serine protease family, Kallikreins</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

KLK6 Protein (Kallikrein 6)

Overview

Klk6 Protein plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Introduction

Kallikrein 6 (KLK6), also known as protease M or neurosin, is a member of the kallikrein family of serine proteases. It is expressed in various tissues including the brain, spinal cord, and peripheral nervous system. KLK6 has been implicated in neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, and multiple system atrophy (MSA), where it plays roles in protein processing, neuroinflammation, and [alpha-synuclein](/mechanisms/alpha-synuclein) metabolism.

Structure

KLK6 has the characteristic structure of trypsin-like serine proteases:

• Signal peptide (aa 1-17): Directs secretion
• Propeptide (aa 18-25): Activation peptide removed by cleavage
• Catalytic domain (aa 26-251): Serine protease active site
• Active site residues: His57, Asp102, Ser195 (chymotrypsin numbering)

Structural Features

• Catalytic triad: His-Asp-Ser protease mechanism
• Disulfide bonds: 6 conserved cysteine residues
• Glycosylation sites: N-linked carbohydrates

Normal Function

Proteolytic Activity

KLK6 is a broad-spectrum protease:

• Extracellular matrix remodeling: Degrades ECM components
• Cytokine processing: Activates/inactivates signaling molecules
• Protein turnover: Cleaves misfolded proteins

Brain Expression

• [Neurons](/entities/neurons): Moderate expression in cortical neurons
• [Astrocytes](/entities/astrocytes): Higher expression in reactive astrocytes
• [Microglia](/entities/microglia): Induced expression in activated [microglia](/cell-types/microglia-neuroinflammation)
• Oligodendrocytes: Present in myelin sheaths

Physiological Roles

• Myelin maintenance: Regulates myelin protein turnover
• Synaptic plasticity: Modulates synaptic proteins
• Neuroprotection: Cleaves toxic protein aggregates
• Wound healing: Involved in tissue repair

Role in Disease

Parkinson's Disease (PD)

KLK6 is critically involved in PD pathogenesis:

• [Alpha-synuclein](/proteins/alpha-synuclein) cleavage: KLK6 can cleave α-synuclein, affecting aggregation
• Dysregulated expression: Altered levels in PD brains
• Enzyme activity changes: Correlation with disease severity
• Protective vs. pathogenic: Dual role in aggregation and clearance

Multiple System Atrophy (MSA)

• Elevated expression: KLK6 increased in MSA brain tissue
• Oligodendrocyte involvement: Role in glial cytoplasmic inclusions
• Disease specificity: Potential biomarker

Alzheimer's Disease

• Amyloid processing: Effects on [Aβ](/proteins/amyloid-beta) metabolism
• [Tau](/proteins/tau) pathology: Interaction with tau protein
• Neuroinflammation: Cytokine activation

Amyotrophic Lateral Sclerosis (ALS)

• Motor neuron expression: Present in affected neurons
• Proteolytic activity: Altered in disease
• Potential biomarker: CSF levels as indicator

Enzyme Activity

Substrate Specificity

KLK6 prefers cleavage after:

• Arginine (R)
• Lysine (K)
• Phenylalanine (F) to lesser extent

Key Substrates

| Substrate | Cleavage Effect |
|-----------|-----------------|
| α-Synuclein | Aggregation modulation |
| Myelin basic protein | Processing |
| Collagen | ECM degradation |
| Cytokines | Activation |

Therapeutic Implications

Drug Development

• Inhibitors: KLK6-specific protease inhibitors
• Activity modulators: Enhance beneficial cleavage
• Biomarker potential: CSF/serum levels

Clinical Applications

• Diagnostic markers: KLK6 in CSF
• Disease progression: Correlation with severity
• Treatment monitoring: Response indicators

Expression Patterns

Regional Distribution

• Substantia nigra: Dopaminergic neurons
• [Cortex](/brain-regions/cortex): Pyramidal neurons
• Spinal cord: Motor neurons
• Peripheral nerves: Sensory neurons

Cellular Localization

• Neuronal soma and processes
• Astrocytic processes
• Microglial lysosomes
• Oligodendrocyte cytoplasm

Animal Models

Knockout Studies

• Klk6-deficient mice show subtle neurological phenotypes
• Altered response to neurotoxic insults
• Changes in protein aggregation models

Key Publications

[Bernett MJ, et al. (2004) KLK6 structure and function. J Biol Chem.](https://doi.org/10.1074/jbc.M403292200)

[Scarisbrick IA, et al. (2002) Kallikrein 6 in neurodegeneration. J Neurosci Res.](https://doi.org/10.1002/jnr.10340)

[Iwata A, et al. (2003) KLK6 and alpha-synuclein. J Biol Chem.](https://doi.org/10.1074/jbc.M306660200)

See Also

• [KLK6 Gene](/klk6-gene)
• [Alpha-Synuclein](/proteins/alpha-synuclein)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Multiple System Atrophy](/diseases/multiple-system-atrophy)
• [Kallikreins](/mechanisms/kallikrein-proteases)
• [Neuroinflammation](/mechanisms/neuroinflammation)

External Links

• [UniProt Q92815](https://www.uniprot.org/uniprot/Q92815)
• [RCSB PDB 1L2E](https://www.rcsb.org/structure/1L2E)
• [NCBI Gene KLK6](https://www.ncbi.nlm.nih.gov/gene/5653)
• [Allen Brain Atlas](https://human.brain-map.org/microarray/search/show?search_term=KLK6)

Overview

Klk6 Protein plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Background

The study of Klk6 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.

References

[Bernett MJ, et al, (2004) (2004)](https://pubmed.ncbi.nlm.nih.gov/15123658/)

[Scarisbrick IA, et al, (2002) (2002)](https://pubmed.ncbi.nlm.nih.gov/12359135/)

[Iwata A, et al, (2003) (2003)](https://pubmed.ncbi.nlm.nih.gov/14527906/)

[Blaber M, et al, (2002) (2002)](https://pubmed.ncbi.nlm.nih.gov/12416974/)

[Diamandis EP, et al, (2004) (2004)](https://pubmed.ncbi.nlm.nih.gov/15046855/)

[Zarghi A, et al, (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/29530366/)

[Okada A, et al, (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20063271/)

[Mitsui S, et al, (2019) (2019)](https://pubmed.ncbi.nlm.nih.gov/31178832/)