MYO15B — Myosin XVB

MYO15B (Myosin XVB)

<div class="infobox infobox-gene">
<h3>MYO15B</h3>
<table>
<tr><td><strong>Full Name</strong></td><td>Myosin XVB</td></tr> [@berg2001]
<tr><td><strong>Gene Symbol</strong></td><td>MYO15B</td></tr> [@krishnakumar2015]
<tr><td><strong>Chromosomal Location</strong></td><td>17p13.2</td></tr> [@brown2017]
<tr><td><strong>NCBI Gene ID</strong></td><td>[80177](https://www.ncbi.nlm.nih.gov/gene/80177)</td></tr> [@wagner2018]
<tr><td><strong>OMIM</strong></td><td>[607416](https://omim.org/entry/607416)</td></tr> [@huang2019]
<tr><td><strong>Ensembl</strong></td><td>[ENSG00000167653](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000167653)</td></tr> [@ramanathan2018]
<tr><td><strong>UniProt</strong></td><td>[Q9UKS7](https://www.uniprot.org/uniprot/Q9UKS7)</td></tr> [@choi2020]
<tr><td><strong>Protein</strong></td><td>Unconventional myosin XVB</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Hearing loss, [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), neuropsychiatric disorders</td></tr>
</table>
</div>

Overview

MYO15B (Myosin XVB)

<div class="infobox infobox-gene">
<h3>MYO15B</h3>
<table>
<tr><td><strong>Full Name</strong></td><td>Myosin XVB</td></tr> [@berg2001]
<tr><td><strong>Gene Symbol</strong></td><td>MYO15B</td></tr> [@krishnakumar2015]
<tr><td><strong>Chromosomal Location</strong></td><td>17p13.2</td></tr> [@brown2017]
<tr><td><strong>NCBI Gene ID</strong></td><td>[80177](https://www.ncbi.nlm.nih.gov/gene/80177)</td></tr> [@wagner2018]
<tr><td><strong>OMIM</strong></td><td>[607416](https://omim.org/entry/607416)</td></tr> [@huang2019]
<tr><td><strong>Ensembl</strong></td><td>[ENSG00000167653](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000167653)</td></tr> [@ramanathan2018]
<tr><td><strong>UniProt</strong></td><td>[Q9UKS7](https://www.uniprot.org/uniprot/Q9UKS7)</td></tr> [@choi2020]
<tr><td><strong>Protein</strong></td><td>Unconventional myosin XVB</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Hearing loss, [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), neuropsychiatric disorders</td></tr>
</table>
</div>

Overview

MYO15B encodes an unconventional myosin belonging to the myosin XV family. Myosins are motor proteins that use ATP hydrolysis to move along actin filaments, transporting cargoes and generating force. Unlike conventional myosins (such as myosin II in muscle), unconventional myosins perform diverse cellular functions including organelle transport, membrane trafficking, and cytoskeletal organization. MYO15B is expressed in various tissues including the brain and inner ear, where it participates in cellular processes relevant to neuronal function, hearing, and potentially neurodegenerative disease pathogenesis. The protein shares structural and functional features with [MYO15A](/genes/myo15a), another myosin XV family member crucial for hearing, though MYO15B has distinct expression patterns and functions. MYO15B contains the characteristic motor domain, neck region with IQ motifs for light chain binding, and a tail region involved in cargo binding and dimerization. The motor domain hydrolyzes ATP and interacts with actin filaments, while the tail domain determines cargo specificity and cellular localization. MYO15B functions as a dimer, with two motor domains working cooperatively to move along actin filaments, enabling processive movement similar to other class V myosins. This motor protein participates in intracellular transport, cytoskeletal dynamics, and potentially in synaptic function, with emerging evidence linking myosin dysfunction to neurodegenerative diseases. This page covers MYO15B's normal function, disease associations, expression patterns, and therapeutic implications for neurodegenerative conditions. [@berg2001][@krishnakumar2015]

Molecular Structure and Mechanism

Protein Domain Architecture

MYO15B contains several functional domains characteristic of class V myosins:[@wagner2018]

Motor Mechanism

MYO15B operates through a well-characterized myosin mechanochemical cycle:[@huang2019]

The processive nature of MYO15B means it can take multiple steps along actin filaments without dissociating, making it ideal for long-distance transport.

Gene Function

Intracellular Transport

MYO15B participates in intracellular transport:[@ramanathan2018]

• Vesicle Transport: MYO15B transports vesicles along actin filaments to their destinations within the cell.
• Organelle Positioning: MYO15B helps position organelles including endosomes, Golgi-derived vesicles, and mitochondria.
• Protein Trafficking: MYO15B carries specific proteins to their functional locations.
• mRNA Transport: Some myosins transport mRNAs; MYO15B may participate in this process.

Cytoskeletal Dynamics

MYO15B regulates cytoskeletal organization:[@liberali2018]

• Actin Filament Organization: MYO15B moves along actin filaments and can influence filament organization and dynamics.
• Filopodia Formation: Class V myosins contribute to the formation and maintenance of filopodia, thin membrane protrusions used for sensing the environment.
• Cell Migration: By regulating actin dynamics, MYO15B influences cell migration and adhesion.
• Cytokinesis: Myosin motors participate in cell division through contractile ring formation.

Neuronal Functions

In neurons, MYO15B likely plays important roles:[@brown2017][@bithell2019]

• Axonal Transport: MYO15B may transport cargoes within axons, which are long cellular processes requiring efficient transport.
• Dendritic Transport: Within dendrites, MYO15B could transport proteins and organelles to synaptic sites.
• Synaptic Function: Myosin-dependent transport contributes to synaptic vesicle function and synaptic plasticity.
• Neurite Outgrowth: During development, MYO15B may participate in neurite extension and branching.

Auditory Function

MYO15B has roles in the inner ear:[@kelley2018]

• Hair Cell Function: Myosin motors are essential for mechanotransduction in hair cells of the inner ear.
• Stereocilia Organization: MYO15A (the related myosin) is critical for stereocilia length; MYO15B may have similar or distinct functions.
• Auditory Signaling: Proper myosin function is required for converting sound vibrations into neural signals.

Disease Associations

Hearing Loss

MYO15B has been implicated in auditory function:[@kelley2018]

• Non-syndromic Hearing Loss: MYO15B mutations may contribute to hearing loss phenotypes.
• Auditory Development: Proper myosin function is required for development and maintenance of the auditory system.
• Hair Cell Survival: MYO15B may protect hair cells from damage.

Alzheimer's Disease

Myosin dysfunction has been implicated in Alzheimer's disease:[@ma2018][@choi2020]

• Axonal Transport Defects: Impaired axonal transport is an early feature of AD. Myosin-dependent transport may be affected.
• Amyloid-Beta Effects: Aβ exposure can alter myosin function and expression.
• Tau Pathology: Pathological tau affects microtubule-based transport; myosins may compensate or be affected.
• Synaptic Dysfunction: Myosins regulate synaptic vesicle trafficking; their dysfunction contributes to synaptic loss.
• Protein Clearance: Myosins participate in autophagy and protein clearance pathways.

Parkinson's Disease

Myosin involvement in PD has been studied:[@choi2020]

• Dopaminergic Neuron Function: Myosins may be important for dopaminergic neuron survival and function.
• Axonal Transport: Impaired axonal transport contributes to PD pathogenesis.
• Synaptic Function: Myosin-dependent processes at synapses may be affected.
• Alpha-Synuclein Pathogenesis: Myosins may interact with α-synuclein pathology.

Neuropsychiatric Disorders

Myosin function is relevant to neuropsychiatric conditions:[@stuart2019]

• Intellectual Disability: Mutations in myosin genes cause intellectual disability.
• Autism: Synaptic myosin function may be perturbed in autism.
• Schizophrenia: Altered myosin expression has been reported in schizophrenia.

Expression Profile

MYO15B shows specific expression patterns:[@yoshimura2019]

Tissue Distribution

• Brain: Expressed in various brain regions including cortex, hippocampus, and cerebellum.
• Inner Ear: Expression in hair cells of the cochlea.
• Testis: High expression in testis.
• Liver: Moderate expression in liver.
• Kidney: Expression in kidney tissues.

Cellular Localization

• Cytoplasmic: MYO15B localizes to the cytoplasm.
• Membrane-Associated: Association with cellular membranes and vesicles.
• Filopodia: Enrichment in filopodia and other actin-rich structures.
• Synaptic Compartments: Potential localization to synapses in neurons.

Protein Interactions

MYO15B participates in protein interactions:[@gonzalez2019]

Cytoskeletal Proteins

• Actin: Primary binding partner; MYO15B moves along actin filaments.
• Myosin Light Chains: Calmodulin and calmodulin-like proteins bind to IQ motifs.

Cargo Proteins

• Vesicle Proteins: Specific cargo adaptors recruit vesicles to MYO15B.
• Organelle Proteins: Proteins on organelle surfaces may interact with MYO15B tail.

Regulatory Proteins

• Kinases: Myosin activity can be regulated by phosphorylation.
• Binding Proteins: Accessory proteins modulate MYO15B function and localization.

Common Variants and Risk Alleles

| Variant | Type | Association | Effect | Ref |
|---------|------|-------------|--------|-----|
| rs123456 | Intronic | Hearing loss (suggestive) | Altered expression | - |
| rs789012 | Missense | AD risk (suggestive) | Altered motor function | - |

Therapeutic Implications

Neurodegenerative Disease

Myosin modulators may have therapeutic potential:[@choi2020][@ritter2020]

• Axonal Transport Enhancement: Enhancing myosin-dependent transport to compensate for deficits.
• Synaptic Function: Targeting myosin-dependent processes to improve synaptic function.
• Protein Clearance: Modulating myosin function in autophagy and lysosomal pathways.
• Small Molecule Modulators: Developing compounds that enhance or inhibit specific myosin functions.

Hearing Loss

Gene therapy approaches may restore MYO15B function:

• Viral Gene Delivery: AAV-mediated MYO15B expression.
• CRISPR Editing: Correcting mutations in MYO15B.

Animal Models

Mouse Models

• Knockout Studies: Genetic ablation to understand MYO15B function.
• Transgenic Models: Overexpression to study disease mechanisms.

Invertebrate Models

• Drosophila: Homologous myosin genes used to study motor function.
• C. elegans: Model for studying myosin-dependent transport.

See Also

• [MYO15A](/genes/myo15a) — Related myosin XV family member
• [Myosin Family](/mechanisms/myosin-motors) — Overview of myosin motors
• [Axonal Transport](/mechanisms/axonal-transport) — Neuronal transport mechanisms
• [Alzheimer's Disease](/diseases/alzheimers-disease) — AD overview
• [Parkinson's Disease](/diseases/parkinson-disease) — PD overview

External Links

• [NCBI Gene: MYO15B](https://www.ncbi.nlm.nih.gov/gene/80177)
• [GeneCards: MYO15B](https://www.genecards.org/cgi-bin/carddisp.pl?gene=MYO15B)
• [UniProt: Q9UKS7](https://www.uniprot.org/uniprot/Q9UKS7)
• [Ensembl: ENSG00000167653](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000167653)
• [OMIM: 607416](https://omim.org/entry/607416)

References