TNNT1

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TnT TnI gene pairs

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TNNT1 gene phylogenic tree

Skeletal troponin complex structure

TNNT1 (Tropomyosin-binding troponin T type 1), also known as slow skeletal troponin T, is a protein that in humans is encoded by the TNNT1 gene. This protein is a critical component of the troponin complex, which is a key regulator of skeletal muscle contraction. The troponin complex is located on the thin filament of the muscle fibers and is composed of three subunits: troponin C, which binds calcium ions; troponin I, which inhibits actin-myosin interactions; and troponin T, which binds to tropomyosin, anchoring the troponin complex to the thin filaments.

Function

The TNNT1 gene product, slow skeletal troponin T, plays an essential role in the regulation of skeletal muscle contraction. It does this by mediating the position of tropomyosin on the thin filament, which, in turn, controls the accessibility of myosin binding sites on actin molecules. When calcium levels increase in the muscle cell, calcium binds to troponin C, causing a conformational change in the troponin complex. This change moves tropomyosin away from the myosin-binding sites on actin, allowing myosin to bind to actin and initiate muscle contraction. As calcium levels fall, the process is reversed, and the muscle relaxes.

Clinical Significance

Mutations in the TNNT1 gene have been associated with a rare condition known as Nemaline myopathy 5 (NEM5), also known as Amish nemaline myopathy. This condition is characterized by muscle weakness, typically beginning in infancy, and is caused by a mutation that leads to the production of an abnormal version of slow skeletal troponin T. This abnormal protein disrupts the normal function of the troponin complex, impairing muscle contraction and leading to the symptoms of the disease.

Genetic

The TNNT1 gene is located on the long (q) arm of chromosome 19 at position 13.4, more precisely at 19q13.4. It spans a length of base pairs and consists of multiple exons, which are segments of the gene that code for the protein. The gene's structure and function are highly conserved among different species, indicating its crucial role in muscle function.

See Also

• Troponin
• Skeletal muscle
• Muscle contraction
• Nemaline myopathy