4.13 Thin Filament Regulation

The review summarizes the current state of knowledge of the calcium regulation of striated muscle contraction via the thin filament proteins, tropomyosin and troponin. The description focuses on in vitro studies of the thin filament and covers structural, biochemical and dynamic aspects of the thin filament's response to calcium binding. A reductionist approach has allowed many of the transitions to be defined at the level of a single structural unit. Here an emphasis is placed on the co-operative nature of the structural and biochemical transitions of the thin filament and the allosteric relationship between calcium and myosin binding to the thin filament.