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Tropomyosin double helix
Mass / length primary structure 568 = 284 + 284 amino acids
Secondary to quaternary structure α + β
Gene name (s) TPM1 , TPM2 , TPM3 , TPM4
External IDs

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:

If calcium ions bind to troponin C, the troponin / tropomyosin complex changes its conformation and thus releases the myosin binding sites , which enables contraction.

Individual evidence

  1. UniProt P09493 , UniProt P06753 , UniProt P07951
  2. UniProt P63316