HMG20B
High Mobility Group 20B: A Chromatin Regulator in Neuronal Development and Cancer
Gene Information Card
| Symbol | HMG20B |
|---|---|
| Full Name | High Mobility Group 20B |
| Gene Type | Protein coding |
| Chromosomal Location | 19p13.3 |
| NCBI Gene ID | 10362 ncbi.nlm.nih.gov/gene/10362 |
| Ensembl ID | ENSG00000104973 |
| UniProt ID | Q9P0W2 |
| OMIM ID | 605535 |
| HGNC ID | 5002 |
| Aliases | iBRAF, HMGX2, SMARCE1-related, BRAF35 |
Description
HMG20B encodes a member of the high mobility group (HMG) protein family that contains an HMG box DNA-binding domain. The protein is a component of chromatin remodeling complexes, including the BRAF35 complex, and plays a critical role in transcriptional regulation, particularly during neuronal differentiation. HMG20B acts as a repressor of neuronal genes in non-neuronal cells and is required for proper brain development. It also interacts with SMARCC1 and other SWI/SNF complex subunits. Mutations and altered expression of HMG20B have been implicated in intellectual disability and various cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Intellectual disability, autosomal dominant 63 | Missense mutations in HMG20B disrupt chromatin remodeling and neuronal gene regulation | ClinVar; PMID: 28554332 |
| Breast cancer | Overexpression of HMG20B promotes proliferation and invasion via chromatin remodeling | COSMIC; PMID: 23431137 |
| Glioblastoma | HMG20B is upregulated and associated with poor prognosis | COSMIC; PMID: 25631443 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 8.2 | Medium |
| Testis | 6.5 | Medium |
| Lung | 4.1 | Low |
| Liver | 2.3 | Low |
| Heart | 3.0 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| SH-SY5Y (neuroblastoma) | 12.5 | Neuronal model |
| HeLa (cervical carcinoma) | 9.8 | High expression |
| MCF7 (breast cancer) | 11.2 | High expression |
| HEK293 (embryonic kidney) | 7.4 | Moderate expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.389G>A (p.Arg130His) | Missense | Rare | Loss of DNA binding; associated with intellectual disability |
| c.502C>T (p.Arg168Trp) | Missense | Rare | Impaired interaction with SMARCC1 |
| c.1A>G (p.Met1?) | Start loss | Very rare | Loss of protein expression |
Mutation functional classification
Loss of Function (LOF)
Missense mutations (e.g., Arg130His) reduce DNA binding and transcriptional repression, leading to neuronal gene derepression.
Gain of Function (GOF)
Not reported.
Dominant Negative (DN)
Some missense variants may act dominant-negative by disrupting complex assembly.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Chromatin remodeling by SWI/SNF complexes (Reactome: R-HSA-5250913)
• Transcriptional regulation by SMARCC1 (Reactome: R-HSA-212300)
Protein Summary
HMG20B is a 35 kDa nuclear protein containing a single HMG box domain that binds DNA in a sequence-specific manner. It is a core component of the BRAF35 complex, which modulates chromatin structure and gene expression. The protein interacts with SMARCC1 (BAF155) and other SWI/SNF subunits to repress neuronal genes in non-neuronal tissues. During neurogenesis, HMG20B is downregulated to allow expression of neuronal differentiation genes. Its structure includes an N-terminal HMG box and a C-terminal domain involved in protein-protein interactions.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| HMG20B Knockout HEK293 Cell Line | EDJ-KQ50961 | Human | 10362 | Details Get a Quote |
| HMG20B Knockout HeLa Cell Line | EDJ-KQ55392 | Human | 10362 | Details Get a Quote |
| HMG20B Knockout A-549 Cell Line | EDJ-KQ63872 | Human | 10362 | Details Get a Quote |
| HMG20B Knockout HCT 116 Cell Line | EDJ-KQ72329 | Human | 10362 | Details Get a Quote |
