Myosin - wikipedia Myosin 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 - / ) 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 term was originally used to describe a group of similar ATPases found in the cells of both striated muscle tissue and smooth muscle tissue. Following the discovery by Pollard and Korn ( 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. 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. Contents 1 Structure and function 1.1 Domains 1.2 Power stroke 2 Nomenclature, evolution, and the family tree 2.1 Myosin classes 2.1. 1 Myosin I 2.1. 2 Myosin II 2.1. 3 Myosin III 2.1. 4 Myosin IV 2.1. 5 Myosin V 2.1. 6 Myosin VI 2.1. 7 Myosin VII 2.1. 8 Myosin VIII 2.1. 9 Myosin IX 2.1. 10 Myosin X 2.1. 11 Myosin XI 2.1. 12 Myosin XII 2.1. 13 Myosin XIII 2.1. 14 Myosin XIV 2.1. 15 Myosin XV 2.1. 16 Myosin XVI 2.1. 17 Myosin XVII 2.1. 18 Myosin XVIII 3 Genes in humans 4 Paramyosin 5 See also 6 References 7 Further reading 8 Additional images 9 External links Structure and function Domains Most myosin molecules are composed of a head, neck, and tail domain. The head domain binds the filamentous actin, and uses ATP hydrolysis to generate force and to `` walk '' along the filament towards the barbed ( + ) end ( with the exception of myosin VI, which moves towards the pointed ( - ) end ). the neck domain acts as a linker and as a lever arm for transducing force generated by the catalytic motor domain. The neck domain can also serve as a binding site for myosin light chains which are distinct proteins that form part of a macromolecular complex and generally have regulatory functions. The tail domain generally mediates interaction with cargo molecules and / or other myosin subunits. In some cases, the tail domain may play a role in regulating motor activity. Power stroke Main article : Muscle contraction Multiple myosin II molecules generate force in skeletal muscle through a power stroke mechanism fuelled by the energy released from ATP hydrolysis. The power stroke occurs at the release of phosphate from the myosin molecule after the ATP hydrolysis while myosin is tightly bound to actin. The effect of this release is a conformational change in the molecule that pulls against the actin. The release of the ADP molecule leads to the so - called rigor state of myosin. The binding of a new ATP molecule will release myosin from actin. ATP hydrolysis within the myosin will cause it to bind to actin again to repeat the cycle. The combined effect of the myriad power strokes causes the muscle to contract. Nomenclature, evolution, and the family tree Myosin unrooted phylogenetic tree The wide variety of myosin genes found throughout the eukaryotic phyla were named according to different schemes as they were discovered. The nomenclature can therefore be somewhat confusing when attempting to compare the functions of myosin proteins within and between organisms. Skeletal muscle myosin, the most conspicuous of the myosin superfamily due to its abundance in muscle fibers, was the first to be discovered. This protein makes up part of the sarcomere and forms macromolecular filaments composed of multiple myosin subunits. Similar filament - forming myosin proteins were found in cardiac muscle, smooth muscle, and nonmuscle cells. However, beginning in the 1970s, researchers began to discover new myosin genes in simple eukaryotes encoding proteins that acted as monomers and were therefore entitled Class I myosins. These new myosins were collectively termed `` unconventional myosins '' and have been found in many tissues other than muscle. These new superfamily members have been grouped according to phylogenetic relationships derived from a comparison of the amino acid sequences of their head domains, with each class being assigned a Roman numeral ( see phylogenetic tree ). The unconventional myosins also have divergent tail domains, suggesting unique functions. The now diverse array of myosins likely evolved from an ancestral precursor ( see picture ). Analysis of the amino acid sequences of different myosins shows great variability among the tail domains, but strong conservation of head domain sequences. Presumably this is so the myosins may interact, via their tails, with a large number of different cargoes, while the goal in each case -- to move along actin filaments -- remains the same and therefore requires the same machinery in the motor. For example, the human genome contains over 40 different myosin genes. These differences in shape also determine the speed at which myosins can move along actin filaments. The hydrolysis of ATP and the subsequent release of the phosphate group causes the `` power stroke, '' in which the `` lever arm '' or `` neck '' region of the heavy chain is dragged forward. Since the power stroke always moves the lever arm by the same angle, the length of the lever arm determines the displacement of the cargo relative to the actin filament. A longer lever arm will cause the cargo to traverse a greater distance even though the lever arm undergoes the same angular displacement -- just as a person with longer legs can move farther with each individual step. The velocity of a myosin motor depends upon the rate at which it passes through a complete kinetic cycle of ATP binding to the release of ADP. Myosin classes Myosin I Myosin I, a ubiquitous cellular protein, functions as monomer and functions in vesicle transport. It has step size of 10 nm and has been implicated as being responsible for the adaptation response of the stereocilia in the inner ear. Myosin II Sliding filament model of muscle contraction. Myosin II ( also known as conventional myosin ) is the myosin type responsible for producing muscle contraction in muscle cells. Myosin II contains two heavy chains, each about 2000 amino acids in length, which constitute the head and tail domains. Each of these heavy chains contains the N - terminal head domain, while the C - terminal tails take on a coiled - coil morphology, holding the two heavy chains together ( imagine two snakes wrapped around each other, as in a caduceus ). Thus, myosin II has two heads. The intermediate neck domain is the region creating the angle between the head and tail. In smooth muscle, a single gene ( MYH11 ) codes for the heavy chains myosin II, but splice variants of this gene result in four distinct isoforms. It also contains 4 myosin light chains ( MLC ), resulting in 2 per head, weighing 20 ( MLC ) and 17 ( MLC ) kDa. These bind the heavy chains in the `` neck '' region between the head and tail. The MLC is also known as the regulatory light chain and actively participates in muscle contraction. The MLC is also known as the essential light chain. Its exact function is unclear, but is believed to contribute to the structural stability of the myosin head along with MLC. Two variants of MLC ( MLC ) exist as a result of alternative splicing at the MLC gene. In muscle cells, the long coiled - coil tails of the individual myosin molecules join together, forming the thick filaments of the sarcomere. The force - producing head domains stick out from the side of the thick filament, ready to walk along the adjacent actin - based thin filaments in response to the proper chemical signals. Further information : Muscle contraction Further information : Meromyosin Myosin III Myosin III is a poorly understood member of the myosin family. It has been studied in vivo in the eyes of Drosophila, where it is thought to play a role in phototransduction. A human homologue gene for myosin III, MYO3A, has been uncovered through the Human Genome Project and is expressed in the retina and cochlea. Myosin IV Myosin IV has a single IQ motif and a tail that lacks any coiled - coil forming sequence. It has homology similar to the tail domains of Myosin VII and XV. Myosin V Crystal structure of myosin V motor with essential light chain -- nucleotide - free Myosin V is an unconventional myosin motor, which is processive as a dimer and has a step size of 36 nm. It translocates ( walks ) along actin filaments traveling towards the barbed end ( + end ) of the filaments. Myosin V is involved in the transport of cargo ( e.g. RNA, vesicles, organelles, mitochondria ) from the center of the cell to the periphery, but has been furthermore shown to act like a dynamic tether, retaining vesicles and organelles in the actin - rich periphery of cells. A recent single molecule in vitro reconstitution study on assembling actin filaments suggests that Myosin V travels farther on newly assembling ( ADP - Pi rich ) F - actin, while processive runlengths are shorter on older ( ADP - rich ) F - actin. Myosin VI State of myosin VI from PDB 2V26 before the power stroke Myosin VI is an unconventional myosin motor, which is primarily processive as a dimer, but also acts as a nonprocessive monomer. It walks along actin filaments, travelling towards the pointed end ( - end ) of the filaments. Myosin VI is thought to transport endocytic vesicles into the cell. Myosin VII Myosin VII is an unconventional myosin with two FERM domains in the tail region. It has an extended lever arm consisting of five calmodulin binding IQ motifs followed by a single alpha helix ( SAH ). Myosin VII is required for phagocytosis in Dictyostelium discoideum, spermatogenesis in C. elegans and stereocilia formation in mice and zebrafish. Myosin VIII Myosin VIII is a plant - specific myosin linked to cell division ; specifically, it is involved in regulating the flow of cytoplasm between cells and in the localization of vesicles to the phragmoplast. Myosin IX Myosin IX is a group of single - headed motor proteins. It was first shown to be minus - end directed, but a later study showed that it is plus - end directed. The movement mechanism for this myosin is poorly understood. Myosin X Myosin X is an unconventional myosin motor, which is functional as a dimer. The dimerization of myosin X is thought to be antiparallel. This behavior has not been observed in other myosins. In mammalian cells, the motor is found to localize to filopodia. Myosin X walks towards the barbed ends of filaments. Some research suggests it preferentially walks on bundles of actin, rather than single filaments. It is the first myosin motor found to exhibit this behavior. Myosin XI Myosin XI directs the movement of organelles such as plastids and mitochondria in plant cells. It is responsible for the light - directed movement of chloroplasts according to light intensity and the formation of stromules interconnecting different plastids. Myosin XII Myosin XIII Myosin XIV This myosin group has been found in the Apicomplexa phylum. The myosins localize to plasma membranes of the intracellular parasites and may then be involved in the cell invasion process. This myosin is also found in the ciliated protozoan Tetrahymena thermaphila. Known functions include : transporting phagosomes to the nucleus and perturbing the developmentally regulated elimination of the macronucleus during conjugation. Myosin XV Myosin XV is necessary for the development of the actin core structure of the non-motile stereocilia located in the inner ear. It is thought to be functional as a monomer. Myosin XVI Myosin XVII Myosin XVIII Genes in humans Note that not all of these genes are active. Class I : MYO1A, MYO1B, MYO1C, MYO1D, MYO1E, MYO1F, MYO1G, MYO1H Class II : MYH1, MYH2, MYH3, MYH4, MYH6, MYH7, MYH7B, MYH8, MYH9, MYH10, MYH11, MYH13, MYH14, MYH15, MYH16 Class III : MYO3A, MYO3B Class V : MYO5A, MYO5B, MYO5C Class VI : MYO6 Class VII : MYO7A, MYO7B Class IX : MYO9A, MYO9B Class X : MYO10 Class XV : MYO15A Class XVIII : MYO18A, MYO18B Myosin light chains are distinct and have their own properties. They are not considered `` myosins '' but are components of the macromolecular complexes that make up the functional myosin enzymes. Light chain : MYL1, MYL2, MYL3, MYL4, MYL5, MYL6, MYL6B, MYL7, MYL9, MYLIP, MYLK, MYLK2, MYLL1 Paramyosin Paramyosin is a large, 93 - 115kDa muscle protein that has been described in a number of diverse invertebrate phyla. Invertebrate thick filaments are thought to be composed of an inner paramyosin core surrounded by myosin. The myosin interacts with actin, resulting in fibre contraction. Paramyosin is found in many different invertebrate species, for example, Brachiopoda, Sipunculidea, Nematoda, Annelida, Mollusca, Arachnida, and Insecta. Paramyosin is responsible for the `` catch '' mechanism that enables sustained contraction of muscles with very little energy expenditure, such that a clam can remain closed for extended periods. See also Actin Motor protein References Jump up ^ `` Myosin ''. Merriam - Webster Dictionary. Jump up ^ `` myosin - definition of myosin in English from the Oxford dictionary ''. OxfordDictionaries.com. Retrieved 2016 - 01 - 20. ^ Jump up to : Pollard, Thomas D. ; Korn, Edward D. ( 1973 ). `` Acanthamoeba myosin. I. Isolation from Acanthamoeba castellanii of an enzyme similar to muscle myosin. '' The Journal of Biological Chemistry. 248 ( 13 ) : 4682 -- 90. PMID 4268863. Jump up ^ McMahon, T.A. 1984. Muscles, Reflexes and Locomotion. 1st Edition. Princeton University Press. ISBN 978 - 0 - 691 - 02376 - 2 Jump up ^ Tyska, Matthew J. ; Warshaw, David M. ( 2002 ). `` The myosin power stroke ''. Cell Motility and the Cytoskeleton. 51 ( 1 ) : 1 -- 15. doi : 10.1002 / cm. 10014. PMID 11810692. Jump up ^ von der Ecken, J. ; Heissler, Sarah M. ; Pathan - Chhatbar, S. ; Manstein, D.J. ; Raunser, S. ( 2016 ). `` Cryo - EM structure of a human cytoplasmic actomyosin complex at near - atomic resolution ''. Nature. 534 ( 7609 ) : 724 -- 728. doi : 10.1038 / nature18295. PMID 27324845. Jump up ^ Cheney, Richard E. ; Mooseker, Mark S. ( 1992 ). `` Unconventional myosins ''. Current Opinion in Cell Biology. 4 ( 1 ) : 27 -- 35. doi : 10.1016 / 0955 - 0674 ( 92 ) 90055 - H. PMID 1558751. Jump up ^ Cheney, Richard E. ; Riley, Margaret A. ; Mooseker, Mark S. ( 1993 ). `` Phylogenetic analysis of the myosin superfamily ''. Cell motility and the cytoskeleton. 24 ( 4 ) : 215 -- 23. doi : 10.1002 / cm. 970240402. PMID 8477454. Jump up ^ Goodson, HV ( 1994 ). `` Molecular evolution of the myosin superfamily : application of phylogenetic techniques to cell biological questions ''. Society of General Physiologists series. 49 : 141 -- 57. PMID 7939893. Jump up ^ Hodge, Tony ; Cope, M. Jamie T.V. ( 2000 ). `` A myosin family tree ''. Journal of Cell Science. 113 ( 19 ) : 3353 -- 4. PMID 10984423. Jump up ^ Berg, Jonathan S. ; Powell, Bradford C. ; Cheney, Richard E. ( 2001 ). `` A Millennial Myosin Census ''. Molecular Biology of the Cell. 12 ( 4 ) : 780 -- 94. doi : 10.1091 / mbc. 12.4. 780. PMC 32266. PMID 11294886. Jump up ^ Oliver, T.N. ; Berg, J.S. ; Cheney, R.E. ( 1999 ). `` Tails of unconventional myosins ''. Cellular and Molecular Life Sciences. 56 ( 3 -- 4 ) : 243 -- 57. doi : 10.1007 / s000180050426. PMID 11212352. Jump up ^ Sutherland Macive ( June 4, 2003 ). `` Myosin I ''. Archived from the original on June 2, 2007. Retrieved 2007 - 05 - 23. Jump up ^ Batters, Christopher ; Arthur, Christopher P ; Lin, Abel ; Porter, Jessica ; Geeves, Michael A ; Milligan, Ronald A ; Molloy, Justin E ; Coluccio, Lynne M ( 2004 ). `` Myo1c is designed for the adaptation response in the inner ear ''. The EMBO Journal. 23 ( 7 ) : 1433 -- 40. doi : 10.1038 / sj. emboj. 7600169. PMC 391074. PMID 15014434. ^ Jump up to : Aguilar, H.N. ; Mitchell, S. ; Knoll, A.H. ; Yuan, X. ( 2010 ). `` Physiological pathways and molecular mechanisms regulating uterine contractility ''. Human Reproduction Update. 16 ( 6 ) : 725 -- 744. doi : 10.1093 / humupd / dmq016. PMID 20551073. Jump up ^ Matsuoka, R. ; Yoshida, M.C. ; Furutani, Y. ; Imamura, S.I. ; Kanda, N. ; Yanagisawa, M. ; Masaki, T. ; Takao, A. ( 1993 ). `` Human smooth muscle myosin heavy chain gene mapped to chromosomal region 16q12 ''. American Journal of Medical Genetics. 46 ( 1 ) : 61 -- 67. doi : 10.1002 / ajmg. 1320460110. PMID 7684189. Jump up ^ http://www.bms.ed.ac.uk/research/others/smaciver/Myosin%20III.htm Jump up ^ EntrezGene 53904 Jump up ^ Sellers, James R. ( 2000 ). `` Myosins : a Diverse Superfamily ''. Biochimica et Biophysica Acta. 1496 ( 1 ) : 3 -- 22. doi : 10.1016 / S0167 - 4889 ( 00 ) 00005 - 7. PMID 10722873. Jump up ^ Mehta, Amit D. ; Ronald S. Rock ; Matthias Rief ; James A. Spudich ; Mark S. Mooseker ; Richard E. Cheney ( 5 August 1999 ). `` Myosin - V is a processive actin - based motor ''. Nature. 400 ( 6744 ) : 590 -- 593. doi : 10.1038 / 23072. PMID 10448864. Jump up ^ Lecuona, E. ; Minin, A. ; Trejo, H.E. ; Chen, J. ; Comellas, A.P. ; Sun, H. ; Grillo, D. ; Nekrasova, O.E. ; Welch, L.C. ; Szleifer, I. ; Gelfand, V.I. ; Sznajder, J.I. ( 6 October 2009 ). `` Myosin - Va restrains the trafficking of Na+ / K+ - ATPase - containing vesicles in alveolar epithelial cells ''. Journal of Cell Science. 122 ( 21 ) : 3915 -- 3922. doi : 10.1242 / jcs. 046953. PMC 2773192. PMID 19808891. Jump up ^ Hammer, John A. ; Sellers, James R. ( 2012 - 01 - 01 ). `` Walking to work : roles for class V myosins as cargo transporters ''. Nature Reviews Molecular Cell Biology. 13 ( 1 ) : 13 -- 26. doi : 10.1038 / nrm3248. ISSN 1471 - 0072. PMID 22146746. Jump up ^ Zimmermann, D ; Santos, A ; Kovar, DR ; Rock, RS. `` Actin Age Orchestrates Myosin - 5 and Myosin - 6 Run Lengths ''. Current Biology. 25 : 2057 -- 2062. doi : 10.1016 / j. cub. 2015.06. 033. PMC 4556227. PMID 26190073. Retrieved 2015 - 12 - 13. Jump up ^ Ménétrey J, Llinas P, Mukherjea M, Sweeney HL, Houdusse A ( 2007 ). `` The structural basis for the large powerstroke of myosin VI ''. Cell. 131 ( 2 ) : 300 -- 8. doi : 10.1016 / j. cell. 2007.08. 027. PMID 17956731. Jump up ^ Buss, Folma ; Kendrick - Jones, John ( 2008 ). `` How are the cellular functions of myosin VI regulated within the cell ? ''. Biochemical and Biophysical Research Communications. 369 ( 1 ) : 165 -- 175. doi : 10.1016 / j. bbrc. 2007.11. 150. PMC 2635068. PMID 18068125. Jump up ^ Buss, Folma ; Spudich, Giulietta ; Kendrick - Jones, John ( 2004 ). `` MYOSIN VI : Cellular Functions and Motor Properties ''. Annual Review of Cell and Developmental Biology. 20 : 649 -- 76. doi : 10.1146 / annurev. cellbio. 20.012103. 094243. PMID 15473855. Jump up ^ Structure. 2017 Apr 4 ; 25 ( 4 ) : 579 - 591. e4. doi : 10.1016 / j. str. 2017.02. 002. Epub 2017 Mar 2. Jump up ^ Schliwa, Manfred, ed. ( 2003 ). Molecular Motors. Wiley - VCH. pp. 516, 518. ISBN 3 - 527 - 30594 - 7. Jump up ^ Reddy, Anireddy S.N. ; Day, Irene S. ( 2001 ). `` Analysis of the myosins encoded in the recently completed Arabidopsis thaliana genome sequence ''. Genome Biology. 2 ( 7 ) : RESEARCH0024. doi : 10.1186 / gb - 2001 - 2 - 7 - research0024. PMC 55321. PMID 11516337. Jump up ^ Baluka, František ; Cvrčková, Fatima ; Kendrick - Jones, John ; Volkmann, Dieter ( 2001 ). `` Sink Plasmodesmata as Gateways for Phloem Unloading. Myosin VIII and Calreticulin as Molecular Determinants of Sink Strength ? ''. Plant Physiology. 126 ( 1 ) : 39 -- 46. doi : 10.1104 / pp. 126.1. 39. PMC 1540107. PMID 11351069. Jump up ^ Reichelt, Stefanie ; Knight, Alex E. ; Hodge, Tony P. ; Baluska, Frantisek ; Samaj, Jozef ; Volkmann, Dieter ; Kendrick - Jones, John ( 1999 ). `` Characterization of the unconventional myosin VIII in plant cells and its localization at the post-cytokinetic cell wall ''. The Plant journal. 19 ( 5 ) : 555 -- 67. doi : 10.1046 / j. 1365 - 313X. 1999.00553. x. PMID 10504577. Jump up ^ Inoue, Akira ; Saito, Junya ; Ikebe, Reiko ; Ikebe, Mitsuo ( 2002 ). `` Myosin IXb is a single - headed minus - end - directed processive motor ''. Nature Cell Biology. 4 ( 4 ) : 302 -- 6. doi : 10.1038 / ncb774. PMID 11901422. Jump up ^ O'Connell, Christopher ; Mooseker, Mark ( 2003 ). `` Native Myosin - IXb is a plus -, not a minus - end - directed motor ''. Nature Cell Biology. 5 ( 2 ) : 171 -- 2. doi : 10.1038 / ncb924. PMID 12563277. Jump up ^ Lu, Qing ; Ye, Fei ; Wei, Zhiyi ; Wen, Zilong ; Zhang, Mingjie ( 2012 ). `` Antiparallel coiled - coil -- mediated dimerization of myosin X ''. Proceedings of the National Academy of Sciences of the United States of America. 109 ( 43 ) : 17388 -- 17393. doi : 10.1073 / pnas. 1208642109. PMC 3491486. PMID 23012428. Jump up ^ Virginie Ropars et al. ( 2016 ). `` The myosin X motor is optimized for movement on actin bundles ''. Nature Communications. 7. doi : 10.1038 / ncomms12456. CS1 maint : Uses authors parameter ( link ) CS1 maint : Explicit use of et al. ( link ) Jump up ^ Sattarzadeh, A. ; Krahmer, J. ; Germain, A.D. ; Hanson, M.R. ( 2009 ). `` A Myosin XI Tail Domain Homologous to the Yeast Myosin Vacuole - Binding Domain Interacts with Plastids and Stromules in Nicotiana benthamiana ''. Molecular Plant. 2 ( 6 ) : 1351 -- 8. doi : 10.1093 / mp / ssp094. PMID 19995734. Jump up ^ Delbac, F. ; Sänger, A ; Neuhaus, EM ; Stratmann, R ; Ajioka, JW ; Toursel, C ; Herm - Götz, A ; Tomavo, S ; Soldati, T ( 2001 ). `` Toxoplasma gondii myosins B / C : one gene, two tails, two localizations, and a role in parasite division ''. The Journal of Cell Biology. 155 ( 4 ) : 613 -- 23. doi : 10.1083 / jcb. 200012116. PMC 2198869. PMID 11706051. Jump up ^ Hettmann, Christine ; Herm, Angelika ; Geiter, Ariane ; Frank, Bernd ; Schwarz, Eva ; Soldati, Thierry ; Soldati, Dominique ( 2000 ). `` A Dibasic Motif in the Tail of a Class XIV Apicomplexan Myosin Is an Essential Determinant of Plasma Membrane Localization ''. Molecular Biology of the Cell. 11 ( 4 ) : 1385 -- 400. doi : 10.1091 / mbc. 11.4. 1385. PMC 14854. PMID 10749937. ^ Jump up to : Winkelman, L ( 1976 ). `` Comparative studies of paramyosins ''. Comparative Biochemistry and Physiology B. 55 ( 3 ) : 391 -- 7. doi : 10.1016 / 0305 - 0491 ( 76 ) 90310 - 2. Jump up ^ Twarog, B.M. ( 1976 ). `` Aspects of smooth muscle function in molluscan catch muscle ''. Physiological Reviews. 56 ( 4 ) : 829 -- 38. doi : 10.1152 / physrev. 1976.56. 4.829. PMID 185635. Further reading Gavin, R.H. ( 2001 ). `` Myosins in protists ''. A Survey of Cell Biology. International Review of Cytology. 206. pp. 97 -- 134. doi : 10.1016 / S0074 - 7696 ( 01 ) 06020 - X. ISBN 978 - 0 - 12 - 364610 - 1. Mooseker, MS ; Cheney, RE ( 1995 ). `` Unconventional Myosins ''. Annual Review of Cell and Developmental Biology. 11 : 633 -- 75. doi : 10.1146 / annurev. cb. 11.110195. 003221. PMID 8689571. Sellers, J ( 2000 ). `` Myosins : a diverse superfamily ''. Biochimica et Biophysica Acta. 1496 ( 1 ) : 3 -- 22. doi : 10.1016 / S0167 - 4889 ( 00 ) 00005 - 7. PMID 10722873. Soldati, Thierry ; Geissler, Heidrun ; Schwarz, Eva C. ( 1999 ). `` How many is enough ? exploring the myosin repertoire in the model eukaryoteDictyostelium discoideum ''. Cell Biochemistry and Biophysics. 30 ( 3 ) : 389 -- 411. doi : 10.1007 / BF02738121. PMID 10403058. Molecular Biology of the Cell. Alberts, Johnson, Lewis, Raff, Roberts, and Walter. 4th Edition. 949 -- 952. Additional images Phase 1 Phase 2 Phase 3 Phase 4 External links Wikimedia Commons has media related to Myosins. MBInfo -- Myosin Isoforms MBInfo -- The Myosin Powerstroke Myosin Video A video of a moving myosin motor protein. Myosins at the US National Library of Medicine Medical Subject Headings ( MeSH ) The Myosin Homepage http://cellimages.ascb.org/cdm4/item_viewer.php?CISOROOT=/p4041coll12&CISOPTR=101&CISOBOX=1&REC=2 Animation of a moving myosin motor protein EC 3.6. 4.1 3D macromolecular structures of myosin from the EM Data Bank ( EMDB ) Proteins of the cytoskeleton Human Microfilaments and ABPs Myofilament Actins A1 A2 C1 G1 G2 Myosins MYO1A MYO1B MYO1C MYO1D MYO1E MYO1F MYO1G MYO1H ) II MYH1 MYH2 MYH3 MYH4 MYH6 MYH7 MYH7B MYH8 MYH9 MYH10 MYH11 MYH13 MYH14 MYH15 MYH16 III MYO3A MYO3B V MYO5A MYO5B MYO5C VI MYO6 VII MYO7A MYO7B IX MYO9A MYO9B X MYO10 XV MYO15A XVIII MYO18A MYO18B LC MYL1 MYL2 MYL3 MYL4 MYL5 MYL6 MYL6B MYL7 MYL9 MYLIP MYLK MYLK2 MYLL1 Other Tropomodulin Troponin Tropomyosin Actinin Arp2 / 3 complex actin depolymerizing factors Cofilin Destrin Gelsolin Profilin Titin Other Wiskott - Aldrich syndrome protein Fibrillin Filamin FLNA FLNB FLNC Espin TRIOBP Intermediate filaments Type 1 / 2 ( Keratin, Cytokeratin ) Epithelial keratins ( soft alpha - keratins ) type I / chromosome 17 10 12 13 14 15 16 17 19 20 chromosome 12 18 none 21 type II / chromosome 12 2A 5 6A 6B 7 8 9 Hair keratins ( hard alpha - keratins ) type I / chromosome 17 31 32 33A 33B 34 35 36 37 38 type II / chromosome 12 81 82 83 84 85 86 Ungrouped alpha chromosome 17 23 24 25 26 27 28 39 40 chromosome 12 71 72 73 74 75 76 77 78 79 80 Not alpha Beta - keratin Type 3 Desmin GFAP Peripherin Vimentin Type 4 Internexin Nestin Neurofilament NEFL NEFM NEFH Synemin Syncoilin Type 5 Nuclear lamins : A / C B1 B2 Microtubules and MAPs Kinesins KIF1A KIF1B KIF2A KIF2C KIF3B KIF3C KIF4A KIF4B KIF5A KIF5B KIF5C KIF6 KIF7 KIF9 KIF11 KIF12 KIF13A KIF13B KIF14 KIF15 KIF16B KIF17 KIF18A KIF18B KIF19 KIF20A KIF20B KIF21A KIF21B KIF22 KIF23 KIF24 KIF25 KIF26A KIF26B KIF27 KIFC1 KIFC2 KIFC3 Dyneins axonemal : DNAH1 DNAH2 DNAH3 DNAH5 DNAH6 DNAH7 DNAH8 DNAH9 DNAH10 DNAH11 DNAH12 DNAH13 DNAH14 DNAH17 DNAI1 DNAI2 DNALI1 DNAL1 DNAL4 cytoplasmic : DYNC1H1 DYNC2H1 DYNC1I1 DYNC1I2 DYNC1LI1 DYNC1LI2 DYNC2LI1 DYNLL1 DYNLL2 DYNLRB1 DYNLRB2 DYNLT1 DYNLT3 Other Tau protein Dynactin DCTN1 Tubulins TUBA1A TUBA1B TUBA1C TUBA3C TUBA3D TUBA3E TUBA4A TUBA8 Stathmin Tektin TEKT1 TEKT2 TEKT3 TEKT4 TEKT5 Dynamin DNM1 DNM2 DNM3 Catenins Alpha catenin Beta catenin APC Plakoglobin ( gamma catenin ) Delta catenin GAN Membrane Dystrophin Dystroglycan Utrophin Ankyrin ANK1 ANK2 ANK3 Spectrin SPTA1 SPTAN1 SPTB SPTBN1 SPTBN2 SPTBN4 SPTBN5 Other Plakins Corneodesmosin Desmoplakin Dystonin Envoplakin MACF1 Periplakin Plectin Talin TLN1 Vinculin Plakophilin PKP1 PKP2 Nonhuman Major sperm proteins Prokaryotic cytoskeleton Crescentin FtsZ MreB See also : cytoskeletal defects Hydrolases : acid anhydride hydrolases ( EC 3.6 ) 3.6. 1 Pyrophosphatase Inorganic Thiamine Apyrase Thiamine - triphosphatase 3.6. 2 Adenylylsulfatase Phosphoadenylylsulfatase 3.6. 3 - 4 : ATPase 3.6. 3 Cu++ ( 3.6. 3.4 ) Menkes / ATP7A Wilson / ATP7B Ca+ ( 3.6. 3.8 ) SERCA ATP2A1 ATP2A2 ATP2A3 Plasma membrane ATP2B1 ATP2B2 ATP2B3 ATP2B4 SPCA ATP2C1 ATP2C2 Na+ / K+ ( 3.6. 3.9 ) ATP1A1 ATP1A2 ATP1A3 ATP1A4 ATP1B1 ATP1B2 ATP1B3 ATP1B4 H+ / K+ ( 3.6. 3.10 ) ATP4A Other P - type ATPase ATP8B1 ATP10A ATP11B ATP12A ATP13A2 ATP13A3 3.6. 4 Dynein Kinesin Myosin Katanin 3.6. 5 : GTPase 3.6. 5.1 : Heterotrimeric G protein GNAI1 GNAI2 GNAI3 GNAQ GNA11 GNA12 GNA13 Transducin GNAT1 GNAT2 Gustducin GNAT3 3.6. 5.2 : Small GTPase > Ras superfamily Rho family of GTPases : Cdc42 CDC42 TC10 TCL RhoUV RhoU RhoV Rac Rac1 RhoG RhoBTB RhoH Rho Rnd RhoDF RhoF RhoD other : Ras HRAS KRAS NRAS Rab RAB23 RAB27 Arf ARF6 SAR1B ARL13B ARL6 Ran Rheb Rap RGK 3.6. 5.3 : Protein - synthesizing GTPase Prokaryotic IF - 2 EF - Tu EF - G Eukaryotic 3.6. 5.5 - 6 : Polymerization motors Dynamin Tubulin Muscle tissue Smooth muscle Calmodulin Vascular smooth muscle Striated muscle Skeletal muscle Costamere / DAPC Membrane / extracellular DAP : Sarcoglycan SGCA SGCB SGCD SGCE SGCG SGCZ Dystroglycan Sarcospan Laminin, alpha 2 Intracellular Dystrophin Dystrobrevin Syntrophin B1 B2 G1 G2 Syncoilin Dysbindin Synemin / desmuslin related : NOS1 Caveolin 3 Sarcomere / ( a, i, and h bands ; z and m lines ) Myofilament thin filament / actin thick filament / myosin elastic filament / titin nebulin Tropomyosin Troponin Connective tissue Epimysium Fascicle Perimysium Endomysium Connective tissue in skeletal muscle General Neuromuscular junction Motor unit Muscle spindle Excitation -- contraction coupling Sliding filament mechanism Cardiac muscle Myocardium Intercalated disc Nebulette Both Fiber Muscle fiber intrafusal extrafusal Myofibril Microfilament / Myofilament Sarcomere Cells Myoblast / Myocyte Myosatellite cell Other Desmin Sarcoplasm Sarcolemma T - tubule Sarcoplasmic reticulum Other / ungrouped Myotilin Telethonin Dysferlin Fukutin Fukutin - related protein Retrieved from `` https://en.wikipedia.org/w/index.php?title=Myosin&oldid=833600087 '' Categories : Proteins Motor proteins Cytoskeleton Skeletal muscle Protein superfamilies Hidden categories : CS1 maint : Uses authors parameter CS1 maint : Explicit use of et al. All articles with dead external links Articles with dead external links from November 2010 Talk Contents About Wikipedia Български Bosanski Català Čeština Deutsch Español Euskara فارسی Français Galego Հայերեն Hrvatski Bahasa Indonesia Íslenska Italiano עברית Қазақша Latviešu Lietuvių Македонски Nederlands 日本 語 Oʻzbekcha / ўзбекча Polski Português Română Русский Simple English Slovenčina کوردی Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska ไทย Türkçe Українська Tiếng Việt 中文 31 more Edit links This page was last edited on 1 April 2018, at 14 : 57. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: where is myosin found in the skeletal muscle cells
Answer: the sarcomere