TPM2 (Tropomyosin 2) encodes the beta-isoform of tropomyosin, an actin-binding protein with essential roles in muscle function and cytoskeletal organization.
TPM2 Protein (Tropomyosin 2) is the beta-isoform of tropomyosin, essential for actin filament stability and muscle contraction. It is expressed in skeletal muscle, cardiac tissue, and neurons, where it participates in cytoskeletal organization.
| Attribute |
Value |
| Protein Name |
Tropomyosin-2 |
| Gene |
TPM2 |
| UniProt ID |
P07951 |
| PDB Structure |
1J3E, 2GJX, 4PJ0 |
| Molecular Weight |
~32.8 kDa |
| Subcellular Localization |
Cytoskeleton, Thin filaments (muscle) |
| Protein Family |
Tropomyosin family |
Tropomyosin-2 shares structural features with other tropomyosin isoforms:
- Coiled-Coil Dimer: Two beta-polypeptide chains form a stable coiled-coil
- Actin-Binding Interface: Continuous binding site along the filament
- Isoform Diversity: Multiple isoforms produced through alternative splicing
- C-terminal Region: Critical for head-to-tail polymerization
The beta-isoform tends to be expressed more in slow-twitch muscle fibers.
- Thin Filament Component: Essential component of skeletal muscle thin filaments
- Contraction Regulation: Tropomyosin shifts position on actin to expose myosin-binding sites
- Calcium Regulation: Cooperates with troponin complex in calcium-dependent regulation
- Actin Filament Organization: Stabilizes specific actin filament populations
- Cell Motility: Regulates actin-dependent cell movements
- Intracellular Transport: Facilitates organelle movement along actin
TPM2 mutations cause nemaline myopathy:
- Autosomal Recessive: Usually inherited in recessive manner
- Muscle Weakness: Characterized by generalized muscle weakness
- Nemaline Rods: Presence of rod-like inclusions in muscle fibers
- Facial Weakness: Often includes facial muscle involvement
TPM2 mutations can cause:
- Hypertrophic Cardiomyopathy: Increased ventricular wall thickness
- Dilated Cardiomyopathy: Ventricular dilation and reduced function
Emerging evidence suggests TPM2 involvement in ALS:
- May contribute to cytoskeletal instability in motor neurons
- Potential for future therapeutic targeting
Current approaches include:
- Myofilament Modifiers: Drugs targeting thin filament function
- Gene Therapy: Potential for future gene replacement
- Protein Stabilizers: Compounds to stabilize mutant TPM2
- Ilkovski et al., TPM2 in nemaline myopathy (2005)
- Wen et al., Tropomyosin mutations in ALS (2016)
- Geeves et al., Tropomyosin function in muscle (2015)