| 背景信息 |
Titin (TTN) is the largest known human protein, functioning as a giant molecular spring and structural scaffold within the sarcomeres of striated muscle. It spans half the length of the sarcomere, from the Z-disc to the M-line, where it interacts with key proteins including telethonin, alpha-actinin, actin, and myosin. Titin is responsible for generating passive tension during muscle stretch and ensuring the precise assembly and alignment of thick filaments. Its extensible I-band region provides elasticity, while its C-terminal kinase domain participates in mechanical strain-dependent signaling. The mechanical properties of titin are further tuned by alternative splicing and post-translational modifications such as phosphorylation. Clinically, truncating variants in the TTN gene are the most common genetic cause of dilated cardiomyopathy (DCM), accounting for approximately 20% of familial cases. |