SGCB Gene - Sarcoglycan Beta
Essential component of the dystrophin-glycoprotein complex; mutations cause limb-girdle muscular dystrophy type R4 (LGMDR4)
Gene Information Card
| Symbol | SGCB |
|---|---|
| Full Name | sarcoglycan beta |
| Gene Type | protein-coding |
| Chromosomal Location | 4q12 |
| NCBI Gene ID | 6443 ncbi.nlm.nih.gov/gene/6443 |
| Ensembl ID | ENSG00000163069 |
| UniProt ID | Q16585 |
| OMIM ID | 600900 |
| HGNC ID | 10805 |
| Aliases | A3b, beta-SG, LGMD2F, LGMDR4 |
Description
SGCB encodes beta-sarcoglycan, a transmembrane glycoprotein that is a component of the dystrophin-glycoprotein complex (DGC). The DGC links the extracellular matrix to the cytoskeleton in muscle cells, providing structural stability. Mutations in SGCB cause limb-girdle muscular dystrophy type R4 (LGMDR4, formerly LGMD2F), an autosomal recessive disorder characterized by progressive proximal muscle weakness.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Limb-girdle muscular dystrophy type R4 (LGMDR4) | Loss-of-function mutations in SGCB disrupt the sarcoglycan complex, destabilizing the DGC and leading to sarcolemmal fragility and muscle fiber degeneration. | ClinVar, OMIM |
| Dilated cardiomyopathy (rare) | Secondary cardiac involvement in LGMDR4 patients due to loss of sarcoglycan complex in cardiac muscle. | OMIM, NCBI Gene |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skeletal muscle | 27.8 | High |
| Heart | 10.2 | Medium |
| Smooth muscle | 5.1 | Low |
| Brain | 0.8 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| LHCN-M2 (myoblast) | 15.3 | Skeletal muscle cell line |
| C2C12 (mouse myoblast) | 12.1 | Mouse ortholog; high expression |
| H9c2 (rat cardiomyoblast) | 8.4 | Cardiac muscle cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.341C>T (p.Thr114Met) | Missense | Rare | Disrupts sarcoglycan complex assembly; pathogenic in LGMDR4 |
| c.271G>A (p.Glu91Lys) | Missense | Rare | Reduced protein stability; associated with LGMDR4 |
| c.1A>G (p.Met1?) | Start loss | Rare | Complete loss of protein; severe LGMDR4 phenotype |
| c.525+1G>A | Splice donor | Rare | Exon skipping; frameshift and premature termination |
Mutation functional classification
Loss of Function (LOF)
Most SGCB mutations are loss-of-function (missense, nonsense, frameshift, splice-site) leading to reduced or absent beta-sarcoglycan protein and disruption of the sarcoglycan complex.
Gain of Function (GOF)
No gain-of-function mutations reported for SGCB.
Dominant Negative (DN)
No dominant-negative mutations reported; inheritance is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Dystrophin-associated glycoprotein complex (DGC) pathway
• Striated muscle contraction pathway
Protein Summary
Beta-sarcoglycan (UniProt Q16585) is a 318-amino acid transmembrane protein with a single transmembrane domain. It forms a subcomplex with alpha-, gamma-, and delta-sarcoglycan within the DGC. The protein is essential for maintaining sarcolemmal integrity during muscle contraction. Defects in beta-sarcoglycan lead to progressive muscular dystrophy.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SGCB Knockout HEK293 Cell Line | EDJ-KQ5741 | Human | 6443 | Details Get a Quote |
| SGCB Knockout HCT 116 Cell Line | EDJ-KQ29140 | Human | 6443 | Details Get a Quote |
| SGCB Knockout HeLa Cell Line | EDJ-KQ29141 | Human | 6443 | Details Get a Quote |
| SGCB Knockout A-549 Cell Line | EDJ-KQ27881 | Human | 6443 | Details Get a Quote |
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