MYH4 (Myosin Heavy Chain 4)
Skeletal muscle myosin heavy chain IIb, a key contractile protein in fast-twitch glycolytic fibers.
Gene Information Card
| Symbol | MYH4 |
|---|---|
| Full Name | Myosin Heavy Chain 4 |
| Gene Type | Protein coding |
| Chromosomal Location | 17p13.1 |
| NCBI Gene ID | 4622 ncbi.nlm.nih.gov/gene/4622 |
| Ensembl ID | ENSG00000180209 |
| UniProt ID | P12883 |
| OMIM ID | 160745 |
| HGNC ID | 7572 |
| Aliases | MyHC-IIb, MyHC-2B, MYH2B |
Description
MYH4 encodes the myosin heavy chain IIb isoform, a major contractile protein expressed predominantly in fast-twitch glycolytic (type IIb) skeletal muscle fibers. This isoform is characterized by high ATPase activity and rapid contraction velocity, essential for explosive movements. MYH4 is part of the myosin heavy chain gene cluster on chromosome 17 and is regulated by neural and hormonal signals.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Myopathy, distal, with rimmed vacuoles (possible) | Altered myosin structure may impair sarcomere integrity | Limited; inferred from MYH2/MYH7 literature |
| Muscle hypertrophy/atrophy phenotypes | Variants affecting myosin ATPase or filament assembly | Case reports and animal models |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skeletal muscle (quadriceps) | High (e.g., 200-400 nTPM) | High |
| Skeletal muscle (gastrocnemius) | High (e.g., 150-350 nTPM) | High |
| Heart | Not detected | Not detected |
| Liver | Not detected | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| LHCN-M2 (human myoblasts) | Low (undifferentiated) | Differentiation increases expression |
| C2C12 (mouse myotubes) | High (differentiated) | Model for fast-twitch myosin |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1234G>A (p.Glu412Lys) | Missense | Rare | Potential altered ATP binding |
| c.2567T>C (p.Leu856Pro) | Missense | Rare | Possible disruption of coiled-coil rod domain |
Mutation functional classification
Loss of Function (LOF)
Nonsense or frameshift variants leading to truncated myosin heavy chain, likely causing loss of contractile function.
Gain of Function (GOF)
Not well documented; missense variants may alter ATPase kinetics but not clearly gain-of-function.
Dominant Negative (DN)
Missense mutations in the rod domain could disrupt filament assembly, exerting dominant-negative effects on sarcomere structure.
View complete mutation data：
Gene Ontology (GO)
| • motor activity (GO:0003774) | • ATP binding (GO:0005524) |
| • myosin complex (GO:0016459) | • muscle filament sliding (GO:0030049) |
| • muscle contraction (GO:0006936) |
Pathways
• Smooth Muscle Contraction (Reactome: R-HSA-397014)
• Muscle contraction (KEGG: hsa04260)
Protein Summary
Myosin heavy chain 4 (MYH4) is a 1939-amino acid protein forming the heavy chain of myosin II in fast-twitch skeletal muscle. It contains an N-terminal globular head domain with ATPase and actin-binding sites, a neck region with light chain binding, and a long alpha-helical coiled-coil tail for filament assembly. MYH4 provides the molecular motor for rapid, glycolytic muscle contraction.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| MYH4 Knockout HEK293 Cell Line | EDJ-KQ5283 | Human | 4622 | Details Get a Quote |
| MYH4 Knockout HeLa Cell Line | EDJ-KQ53940 | Human | 4622 | Details Get a Quote |
| MYH4 Knockout A-549 Cell Line | EDJ-KQ62432 | Human | 4622 | Details Get a Quote |
| MYH4 Knockout HCT 116 Cell Line | EDJ-KQ70899 | Human | 4622 | Details Get a Quote |
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