ACTG2 Gene - Actin Gamma 2, Smooth Muscle
Essential smooth muscle actin gene involved in contractile function and associated with visceral myopathy
Gene Information Card
| Symbol | ACTG2 |
|---|---|
| Full Name | actin gamma 2, smooth muscle |
| Gene Type | protein-coding |
| Chromosomal Location | 2p13.1 |
| NCBI Gene ID | 72 ncbi.nlm.nih.gov/gene/72 |
| Ensembl ID | ENSG00000163017 |
| UniProt ID | P63267 |
| OMIM ID | 102545 |
| HGNC ID | 145 |
| Aliases | ACTG2, ACTA3, ACTL3, ACTSG, gamma-actin, smooth muscle gamma-actin |
Description
ACTG2 (actin gamma 2, smooth muscle) encodes a smooth muscle-specific actin isoform, gamma-2 actin, which is a major component of the contractile apparatus in vascular and visceral smooth muscle cells. This gene is essential for smooth muscle contraction and maintenance of tissue integrity in organs such as the intestine, bladder, and uterus. Mutations in ACTG2 cause autosomal dominant visceral myopathy, including megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) and chronic intestinal pseudo-obstruction.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) | Dominant-negative or loss-of-function mutations in ACTG2 impair smooth muscle contractility, leading to severe intestinal and bladder dysfunction. | ClinVar, OMIM |
| Chronic intestinal pseudo-obstruction | ACTG2 mutations disrupt actin filament polymerization, reducing smooth muscle force generation and causing dysmotility. | ClinVar, OMIM |
| Visceral myopathy | Heterozygous missense mutations in ACTG2 alter actin dynamics, leading to progressive smooth muscle degeneration and fibrosis. | OMIM, NCBI |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Smooth muscle (intestine, bladder, uterus) | High (e.g., >100 nTPM) | High |
| Heart | Low (<10 nTPM) | Low |
| Skeletal muscle | Very low (<1 nTPM) | Not detected |
| Liver | Low (<5 nTPM) | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Primary smooth muscle cells (aortic) | High | Consistent with smooth muscle origin |
| Fibroblasts (lung) | Low | Non-muscle cell type |
| HEK293 | Very low | Embryonic kidney cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.119C>T (p.Arg40Cys) | Missense | Rare (0.0004 in gnomAD) | Dominant-negative; disrupts actin polymerization and contractility |
| c.445G>A (p.Glu149Lys) | Missense | Rare | Gain-of-function?; associated with MMIHS |
| c.769G>A (p.Gly257Arg) | Missense | Rare | Dominant-negative; impairs filament stability |
Mutation functional classification
Loss of Function (LOF)
Homozygous or compound heterozygous loss-of-function mutations are rare; heterozygous missense often act as dominant-negative rather than simple loss-of-function.
Gain of Function (GOF)
Some missense mutations (e.g., p.Glu149Lys) may confer altered actin dynamics, but evidence for true gain-of-function is limited.
Dominant Negative (DN)
Most pathogenic ACTG2 mutations (e.g., p.Arg40Cys, p.Gly257Arg) act via dominant-negative mechanism, disrupting wild-type actin filament assembly and smooth muscle contraction.
View complete mutation data：
Gene Ontology (GO)
| • GO:0005200 - structural constituent of cytoskeleton | • GO:0005515 - protein binding |
| • GO:0005856 - cytoskeleton | • GO:0015629 - actin cytoskeleton |
| • GO:0030048 - actin filament polymerization | • GO:0031032 - actomyosin structure organization |
| • GO:0006936 - muscle contraction |
Pathways
• Smooth muscle contraction (Reactome: R-HSA-445355)
• Actin cytoskeleton regulation (KEGG: hsa04810)
• Cardiac muscle contraction (Reactome: R-HSA-5576891) - minor role
Protein Summary
Gamma-2 actin (UniProt P63267) is a 376-amino acid protein that forms filamentous actin (F-actin) in smooth muscle cells. It is highly conserved among actins and differs from alpha-actin isoforms primarily in the N-terminal region. The protein polymerizes into thin filaments that interact with myosin to generate contractile force. Mutations in the ACTG2 gene disrupt filament assembly and stability, leading to smooth muscle dysfunction and visceral myopathies.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| ACTG2 Knockout HEK293 Cell Line | EDJ-KQ4002 | Human | 72 | Details Get a Quote |
| ACTG2 Knockout HeLa Cell Line | EDJ-KQ26323 | Human | 72 | Details Get a Quote |
| ACTG2 Knockout A-549 Cell Line | EDJ-KQ61025 | Human | 72 | Details Get a Quote |
| ACTG2 Knockout HCT 116 Cell Line | EDJ-KQ69500 | Human | 72 | Details Get a Quote |
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