The anterior portion of the muscle is called the fast muscle, it is striated and contracts to close the leaflets in less than 100 milliseconds. Specifically, what makes it more difficult is the smallest portion of this muscle , which corresponds to the smooth muscle fibers or closure muscle.
This keeps the leaflets immobile when they have been fully or partially closed. Its strength is such that, in theory, perpetuating it over time should consume all the energy of the oyster, which does not happen due to the unique structure of the muscle filaments. In these, each layer of myosin molecules, the fibrous and motor protein, rests on top of another in a layer formed by paramyosin.
The latter controls the assembly and activity of myosin and could become more rigid when it undergoes phosphorylation – the mechanism that regulates the activity of proteins -, without implying a great energy waste. The survival of the mollusk depends on this molecular strategy.
