Myosin is one of the protein molecules that (together
and actin) forms the cylindrical structures called myofibrils that,
together, form muscle
Myofibrils consist of two types of protein filaments, called
filaments, and thick
filaments. Myosin molecules, form the thick filaments,
whose structure is illustrated below (lower image).
Diagram of a single myosin molecule.
Above: Diagram of a Thick Filament
There are approx. 200 myosin molecules forming a typical thick
filament. These molecules are arranged with their "tails" parallel to
each other as illustrated above.
Myosin molecules are important for the process
of muscle contraction. The myosin "heads" or "crossbridges" are attached
to "myosin-binding sites" on positions on another protein called actin,
which is located in the thin filaments of the myofibrils.