Function
Myosin is a type of motor protein, which are proteins that specialize in turning Chemical Energy to mechanical Energy. The protein is commonly found in muscle tissue and is used for motility in eukaryotes. In order for the process to work, myosin uses the subdomains in its head to locate and attach to actin filaments.ATP is brought into the myosin active site, where ATPase hydrolyze the ATP to ADP+Pi.The hydrolyzing leads to tighter binding of the myosin and actin filament.The release of the Pi also leads to even tighter binding.The binding of myosin and actin filament forms what is known as muscle contraction or simply contractions.An additional ATP can be added to the structure to release the actin and have the cycle repeated.
Disease
Common disease related to myosin is Myopathy, which leads to muscle weakness. The is due to mutation of the MYH7 gene that synthesizes the long heavy chain. The mutation causes clumping of the myosin protein. The clumping
stops the myosin from gathering filaments to create good contractions. The lack of this may be leading to the muscle weakness but it still unclear.
Relevance
Myosin is important for eukaryotes. Without these motor proteins there would be no muscle contractions and therefore no way to mobile. Even worse, involuntary muscle such as the heart wouldn't function as well. A mutation of the protein itself as shown to lead to weakness in humans. Lack of the protein completely, would be even more detrimental.
Structural highlights
The labels are the amino acids that make up the subunits of the myosin. Switch(Ile461-Asn470) is orange, Relay (Asn489-Asp515) is red, Sh1 helix(Cys693-Phe707) is cyan, Converter (707-774) is lime and the Long Heavy Chain (775-835) is black. The colors of the label match up to the same labeling used for the ribbon model.
