Part of the myosin II structure. Atoms in the heavy chain are colored pink (on the left-hand side); atoms in the light chains are colored faded-orange and faded-yellow (also on the left-hand side).
Myosins (/ˈmaɪəsɪn,-oʊ-/[1][2]) are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are ATP-dependent and responsible for actin-based motility.
The first myosin (M2) to be discovered was in 1864 by Wilhelm Kühne. Kühne had extracted a viscous protein from skeletal muscle that he held responsible for keeping the tension state in muscle. He called this protein myosin.[3][4] The term has been extended to include a group of similar ATPases found in the cells of both striated muscle tissue and smooth muscle tissue.
Following the discovery in 1973 of enzymes with myosin-like function in Acanthamoeba castellanii, a global range of divergent myosin genes have been discovered throughout the realm of eukaryotes.[5]
Although myosin was originally thought to be restricted to muscle cells (hence myo-(s) + -in), there is no single "myosin"; rather it is a very large superfamily of genes whose protein products share the basic properties of actin binding, ATP hydrolysis (ATPase enzyme activity), and force transduction. Virtually all eukaryotic cells contain myosin isoforms. Some isoforms have specialized functions in certain cell types (such as muscle), while other isoforms are ubiquitous. The structure and function of myosin is globally conserved across species, to the extent that rabbit muscle myosin II will bind to actin from an amoeba.[6]
^"Myosin". Merriam-Webster.com Dictionary.
^"myosin - definition of myosin in English from the Oxford dictionary". OxfordDictionaries.com. Archived from the original on 24 August 2012. Retrieved 20 January 2016.
^Hartman MA, Spudich JA (April 2012). "The myosin superfamily at a glance". Journal of Cell Science. 125 (Pt 7): 1627–1632. doi:10.1242/jcs.094300. PMC 3346823. PMID 22566666.
^Szent-Györgyi AG (June 2004). "The early history of the biochemistry of muscle contraction". The Journal of General Physiology. 123 (6): 631–641. doi:10.1085/jgp.200409091. PMC 2234565. PMID 15173217.
^Pollard TD, Korn ED (July 1973). "Acanthamoeba myosin. I. Isolation from Acanthamoeba castellanii of an enzyme similar to muscle myosin". The Journal of Biological Chemistry. 248 (13): 4682–4690. doi:10.1016/S0021-9258(19)43718-6. PMID 4268863. Archived from the original on 6 January 2016.
^McMahon, T. A. 1984. Muscles, Reflexes and Locomotion. 1st Edition. Princeton University Press. ISBN 978-0-691-02376-2
Myosins (/ˈmaɪəsɪn, -oʊ-/) are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility...
the proteins of myosin and actin which together have the capability to contract. Myosin is primarily class II in smooth muscle. Myosin II contains two...
Myosin ATPase (EC 3.6.4.1) is an enzyme with systematic name ATP phosphohydrolase (actin-translocating). This enzyme catalyses the following chemical reaction:...
"ladder" along which the myosin filaments "climb" to generate motion Thick filaments consist primarily of the protein myosin, that is responsible for...
of the important proteins are myosin, which forms the thick filament, and actin, which forms the thin filament. Myosin has a long, fibrous tail and a...
function without dynein. Numerous myosin deficiencies are related to disease states and genetic syndromes. Because myosin II is essential for muscle contraction...
The myosin head is the part of the thick myofilament made up of myosin that acts in muscle contraction, by sliding over thin myofilaments of actin. Myosin...
triphosphate (ATP). ATP is required to cause the separation of the actin-myosin cross-bridges during relaxation of muscle. When oxygen is no longer present...
promotes myosin II activation by the kinase ROCK, which activates myosin II directly by phosphorylation of the myosin light chain and also inhibits myosin phosphatase...
other to generate movement. According to the sliding filament theory, the myosin (thick filaments) of muscle fibers slide past the actin (thin filaments)...
A myosin light chain is a light chain (small polypeptide subunit) of myosin. Myosin light chains were discovered by Chinese biochemist Cao Tianqin (Tien-chin...
and thick filaments dominantly consist of chains of the motor-protein myosin. Together, these two filaments form myofibrils - the basic functional organelles...
histochemical staining for myosin ATPase activity and immunohistochemical staining for myosin heavy chain (MHC) type. Myosin ATPase activity is commonly—and...
myofibrils in muscle cells. The main proteins involved are myosin, actin, and titin. Myosin and actin are the contractile proteins and titin is an elastic...
Myosin VIIA is protein that in humans is encoded by the MYO7A gene. Myosin VIIA is a member of the unconventional myosin superfamily of proteins. Myosins...
actin-containing thin filaments. The thin filaments are placed between 2 myosin filaments and contain only the actin filaments of neighboring sarcomeres...
Meromyosin is a part of myosin (mero meaning "part of"). With regards to human anatomy myosin and actin constitute the basic functional unit of a muscle...
called myosins travel. Actin plays a particularly prominent role in muscle cells, which consist largely of repeated bundles of actin and myosin II. Each...
the actin filament elongates while the other end contracts, presumably by myosin II molecular motors. Additionally, they function as part of actomyosin-driven...
myogenesis. Muscle tissue contains special contractile proteins called actin and myosin which interact to cause movement. Among many other muscle proteins present...
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