B3GALT6 Gene

B3GALT6 Gene

Overview

The B3GALT6 gene encodes Beta-1,3-Galactosyltransferase 6, a member of the glycosyltransferase family that plays a critical role in the biosynthesis of glycosaminoglycans (GAGs) and proteoglycans. Located on chromosome 2q32.2, this enzyme is essential for the synthesis of the tetrasaccharide linker region that connects glycosaminoglycan chains to the core protein in proteoglycans[mizumoto2012][@kurtoglu2014].

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0; text-align:center;">B3GALT6</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>B3GALT6</td></tr>
<tr><td><strong>Full Name</strong></td><td>Beta-1,3-Galactosyltransferase 6</td></tr>
<tr><td><strong>Chromosomal Location</strong></td><td>2q32.2</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[55503](https://www.ncbi.nlm.nih.gov/gene/55503)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000110717</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q96MC4](https://www.uniprot.org/uniprotkb/Q96MC4/entry)</td></tr>
<tr><td><strong>Protein Category</strong></td><td>Glycosyltransferase (GT31 family)</td></tr>
<tr><td><strong>OMIM</strong></td><td>[614940](https://www.omim.org/entry/614940)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Gene Structure and Evolution

B3GALT6 Gene

Overview

The B3GALT6 gene encodes Beta-1,3-Galactosyltransferase 6, a member of the glycosyltransferase family that plays a critical role in the biosynthesis of glycosaminoglycans (GAGs) and proteoglycans. Located on chromosome 2q32.2, this enzyme is essential for the synthesis of the tetrasaccharide linker region that connects glycosaminoglycan chains to the core protein in proteoglycans[mizumoto2012][@kurtoglu2014].

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0; text-align:center;">B3GALT6</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>B3GALT6</td></tr>
<tr><td><strong>Full Name</strong></td><td>Beta-1,3-Galactosyltransferase 6</td></tr>
<tr><td><strong>Chromosomal Location</strong></td><td>2q32.2</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[55503](https://www.ncbi.nlm.nih.gov/gene/55503)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000110717</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q96MC4](https://www.uniprot.org/uniprotkb/Q96MC4/entry)</td></tr>
<tr><td><strong>Protein Category</strong></td><td>Glycosyltransferase (GT31 family)</td></tr>
<tr><td><strong>OMIM</strong></td><td>[614940](https://www.omim.org/entry/614940)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Gene Structure and Evolution

The B3GALT6 gene spans approximately 8.5 kb and consists of 9 exons. It encodes a type II membrane-bound glycosyltransferase with a short cytoplasmic N-terminus, a transmembrane domain, and a catalytic domain facing the Golgi lumen. The gene is evolutionarily conserved across vertebrates, with orthologs in zebrafish, mice, and humans[byers2012].

Protein Function and Mechanism

B3GALT6 catalyzes the transfer of galactose from UDP-galactose to the growing glycosaminoglycan chain during proteoglycan biosynthesis. Specifically, it functions in the synthesis of the tetrasaccharide linker region (GlcA-β1,3-Gal-β1,3-Gal-β1,4-Xyl) that attaches glycosaminoglycans to the core protein[okajima2007][@guo2015]:

Biochemical Activity

• Substrate: UDP-galactose + acceptor (typically a GlcA-containing trisaccharide)
• Product: Galactosylated tetrasaccharide linker
• Location: Golgi apparatus
• Cooperation: Works together with B4GALT7 (beta-1,4-galactosyltransferase 7) in the linker region synthesis

Substrate Specificity

B3GALT6 shows specificity for:

• Chondroitin sulfate (CS) proteoglycans
• Dermatan sulfate (DS) proteoglycans
• Heparan sulfate (HS) proteoglycans (to lesser extent)

Expression Pattern

B3GALT6 is widely expressed in connective tissues throughout the body:

Tissue Distribution

• Skin: Dermal fibroblasts, especially in collagen-rich areas
• Cartilage: Chondrocytes in articular and growth plate cartilage
• Bone: Osteoblasts and osteocytes
• Brain: Meningeal cells, some glial populations (lower expression)
• Lung: Bronchial epithelium
• Blood vessels: Vascular smooth muscle cells

Role in Extracellular Matrix Assembly

Proteoglycans are critical components of the extracellular matrix that provide structural support, regulate growth factor signaling, and maintain tissue hydration[martens2009]:

Structural Support

• Aggrecan: Major proteoglycan in cartilage, provides compressive resistance
• Decorin: Regulates collagen fibril assembly and tissue tensile strength
• Biglycan: Binds to collagen and influences tissue elasticity

Signaling Regulation

• Growth factor binding: Heparan sulfate proteoglycans (HSPGs) bind FGF, VEGF, and other growth factors
• Morphogen gradients: Proteoglycans regulate morphogen diffusion during development
• Cell adhesion: Syndecans and glypicans mediate cell-ECM interactions

Disease Associations

B3GALT6 Syndrome (Autosomal Recessive)

Recessive mutations in B3GALT6 cause a novel spectrum of connective tissue disorders characterized by[byers2012][@kurtoglu2014]:

• Ehlers-Danlos syndrome (progeroid type): Distinctive facial features, hypermobility, skin fragility
• Arthrochalasia-type EDS: Severe joint hypermobility with congenital dislocation
• Spondyloepimetaphyseal dysplasia: Short stature, skeletal abnormalities

Pathogenic Mechanisms

• Loss of enzymatic function reduces proteoglycan synthesis
• Abnormal glycosaminoglycan chains compromise ECM integrity
• Tissues with high mechanical stress are most affected[herguner2015][@faiyaz2014]

Neurological Involvement

While primarily a connective tissue disorder, B3GALT6-related conditions may present with:

• Developmental delay: Due to altered CNS proteoglycans
• Hypotonia: Decreased muscle tone in infancy
• Connective tissue-related neurological complications: Including some cases of spastic paraplegia[cathey2010]

Implications for Neurodegeneration

Although not directly linked to classic neurodegenerative diseases, glycosyltransferases like B3GALT6 are increasingly recognized in neurodegenerative processes[esko2009][@morvan2019]:

Proteoglycans in Neurodegeneration

• Alzheimer's disease: Heparan sulfate proteoglycans interact with amyloid-beta and tau, influencing plaque formation and neurofibrillary tangle development[yamaguchi2000][@berenson2010]
• Parkinson's disease: Altered proteoglycan metabolism affects alpha-synuclein aggregation
• Axon guidance: Proteoglycans regulate growth cone navigation during development[yamada2014]

Glycosylation and Neuroinflammation

• Alterations in glycosylation patterns affect microglial activation
• Changes in ECM glycosaminoglycans modulate neuroinflammatory responses[uyama2013]

Therapeutic Implications

Understanding glycosyltransferase function may lead to:

• Targeted therapies: Modulating proteoglycan synthesis to influence disease progression
• Biomarkers: Glycosylation patterns as indicators of disease state
• Gene therapy: Restoring enzymatic function in deficiency states

Animal Models

• Zebrafish models: B3GALT6 knockdown shows craniofacial and fin development defects
• Mouse models: Conditional knockouts demonstrate skin and cartilage abnormalities
• Patient-derived cells: Fibroblasts show reduced GAG synthesis capacity

Therapeutic Approaches

Current Strategies

• Symptomatic management: Physical therapy, orthopedic interventions for joint issues
• Monitoring: Regular assessment of cardiac, ophthalmological, and skeletal complications
• Genetic counseling: Family planning and carrier identification

Emerging Therapies

• Enzyme replacement: Potential for supplying functional glycosyltransferase
• Gene therapy: AAV-mediated B3GALT6 delivery
• Small molecule modulators: Enhancing residual enzyme activity

Cross-references

• [Ehlers-Danlos Syndrome](/diseases/ehlers-danlos-syndrome)
• [Hereditary Spastic Paraplegia](/diseases/hereditary-spastic-paraplegia)
• [Spinocerebellar Ataxia](/diseases/spinocerebellar-ataxia)
• [Friedreich Ataxia](/diseases/friedreich-ataxia)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Glycosaminoglycans](/entities/glycosaminoglycans)
• [Extracellular Matrix](/entities/extracellular-matrix)

Key References

Pathway & Interaction Diagram

Interactive diagram showing B3GALT6's key relationships in the SciDEX knowledge graph (6 connections shown).

External Links

• [NCBI Gene: B3GALT6](https://www.ncbi.nlm.nih.gov/gene/55503)
• [UniProt: Q96MC4](https://www.uniprot.org/uniprotkb/Q96MC4/entry)
• [OMIM: 614940](https://www.omim.org/entry/614940)
• [GeneCards: B3GALT6](https://www.genecards.org/cgi-bin/carddisp.pl?gene=B3GALT6)
• [Ensembl: ENSG00000110717](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110717)

References

berenson2010, Heparan sulfate in tau pathology and neurodegenerative diseases (2010)
byers2012, Mutations in B3GALT6 cause a spectrum of connective tissue disorders (2012)
cathey2010, Phenotypic spectrum of B3GALT6-related disorders (2010)
cunningham2016, Glycosyltransferase mutations in skeletal dysplasia (2016)
esko2009, Proteoglycans and glycosaminoglycans in neurodegeneration (2009)
faiyaz2014, A founder mutation in B3GALT6 causes a novel recessive connective tissue disorder (2014)
guo2015, B3GALT6 regulates extracellular matrix assembly and biomechanical properties (2015)
herguner2015, B3GALT6 mutations in patients with Ehlers-Danlos syndrome (2015)
jourdain2018, Proteoglycans at the synapse: from structure to function (2018)
karamanos2019, Glycosaminoglycans in health and disease: The building blocks of life (2019)
kurtoglu2014, B3GALT6 syndrome: a new genetic disorder characterized by connective tissue abnormalities and severe infections (2014)
malfait2015, The 2017 international classification of connective tissue disorders (2015)
martens2009, Proteoglycans in the central nervous system: role in development and disease (2009)
mizumoto2012, Functional analysis of B3GALT6 and B4GALT7 in glycosyltransferase (2012)
morvan2019, Glycosylation in neurodegenerative diseases: An emerging field (2019)
okajima2007, Molecular functions of glycosyltransferases in proteoglycan synthesis (2007)
peyrin2007, The role of proteoglycans in tau aggregation and neurodegeneration (2007)
uyama2013, Disorders of glycosylation in neurological diseases (2013)
yamada2014, Functions of glycosyltransferases in brain development and function (2014)
yamaguchi2000, Glycosaminoglycans and their modifying enzymes in Alzheimer's disease (2000)