Tropomyosin
| Tropomyosin | ||
|---|---|---|
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| Tropomyosin double helix | ||
| Mass / length primary structure | 568 = 284 + 284 amino acids | |
| Secondary to quaternary structure | α + β | |
| Identifier | ||
| Gene name (s) | TPM1 , TPM2 , TPM3 , TPM4 | |
| External IDs | ||
| Parent |
| Microfilament |
| Gene Ontology |
|---|
| QuickGO |
Tropomyosin is a highly conserved actin-binding protein found in eukaryotes from animals to yeast, with the exception of plants. In the human body, it occurs primarily in the skeletal muscles. The biochemist Kenneth Bailey first described the protein in 1946.
Tropomyosins are often divided into two groups, muscle tropomyosin isoforms and non-muscle tropomyosin isoforms. Muscle tropomyosin isoforms are involved in regulating the interactions between actin and myosin in the muscle sarcomere and play a central role in regulated muscle contraction. Non-muscle tropomyosin isoforms function in all cells, both muscle and non-muscle, and are involved in a number of cellular pathways that control and regulate the cell's cytoskeleton and other important cellular functions.
Tropomyosin is a rod-shaped molecule that is approximately 400 Å long, 20 Å wide, and has a molecular mass of 65 to 70 kDa . It consists of two subunits α, β, whereby there are three isoforms of α (α1, α3, α4). In skeletal muscle , tropomyosin makes up about 3% of total muscle protein.
Changes in the genes that code for one of the tropomyosin subunits can lead to hereditary diseases:
- α1:
- Hypertrophic Cardiomyopathy (CMH3)
- Dilated cardiomyopathy (CMD1Y)
- α3:
- β:
- Nemaline myopathy -4 (NEM4)
- Arthrogryposis multiplex congenita (DA1)
If calcium ions bind to troponin C, the troponin / tropomyosin complex changes its conformation and thus releases the myosin binding sites , which enables contraction.