Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Myosin
open-in-new
<p>Myosins are a <a href="/facts/Protein_family/EHt5xwCA">family</a> of <a href="/facts/Motor_protein/g5PE2m9F">motor proteins</a> (though most often protein complexes) best known for their roles in <a href="/facts/Muscle_contraction/EbloCYfV">muscle contraction</a> and in a wide range of other <a href="/facts/Motility/Df5BECHL">motility</a> processes in <a href="/facts/Eukaryote/SkwyPLMA">eukaryotes</a>. They are <a href="/facts/Adenosine_triphosphate/nB9bwgcU">ATP</a>-dependent and responsible for <a href="/facts/Actin/Hu3qIUL9">actin</a>-based motility. </p><p>The first myosin (M2) to be discovered was in 1864 by <a href="/facts/Wilhelm_K%25C3%25BChne/57KvoBgF">Wilhelm Kühne</a>. Kühne had extracted a viscous protein from <a href="/facts/Skeletal_muscle/en1tVYFN">skeletal muscle</a> that he held responsible for keeping the tension state in muscle. He called this protein <i>myosin</i>. The term has been extended to include a group of similar <a href="/facts/ATPase/8aEJlNgl">ATPases</a> found in the <a href="/facts/Cell_(biology)/bLM9UQvy">cells</a> of both <a href="/facts/Striated_muscle_tissue/WYfQuhID">striated muscle tissue</a> and <a href="/facts/Smooth_muscle_tissue/mpcpTsHp">smooth muscle tissue</a>. </p><p>Following the discovery in 1973 of enzymes with myosin-like function in <i><a href="/facts/Acanthamoeba/vgedK72K">Acanthamoeba castellanii</a></i>, a global range of divergent myosin <a href="/facts/Gene/e1swwPY6">genes</a> have been discovered throughout the realm of eukaryotes. </p><p>Although myosin was originally thought to be restricted to <a href="/facts/Muscle_cell/cP7Jea3q">muscle cells</a> (hence <i>myo-</i>(s) + <i>-in</i>), 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 <a href="/facts/Hydrolysis/JTvwIHPs">hydrolysis</a> (ATPase enzyme activity), and force transduction. Virtually all eukaryotic cells contain myosin <a href="/facts/Protein_isoform/oWmzfg4l">isoforms</a>. 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 <a href="/facts/Amoeba/xxvUal7B">amoeba</a>. </p>