Myosins are molecular motors that move or interact with actin filaments to perform a variety of functions in cells. The multiple myosin genes in humans contain a conserved motor domain that harbors the machinery needed to interact with actin and hydrolyze ATP. Other functional domains exist to determine the localization and anchoring of the molecule.

Keywords: myosin; molecular motor; ATPase; motility; deafness; actomyosin; cytoskeleton

Figure 1.

Phylogenetic tree of the human myosin superfamily. Solid lines indicate myosins for which chromosomal deoxyribonucleic acid (cDNA) sequences exist, and dashed lines indicate putative myosins predicted from genomic sequence. Recently discovered or newly predicted myosin genes are italicized, and potential gene names suggested for myosins predicted from genomic sequence are indicated in parentheses. The tree was modified from the one provided by R. Cheney (Berg et al., ).

Figure 2.

Crystal structure of the head of scallop striated muscle myosin. The three‐dimensional structure of the scallop striated muscle head fragment protein 1DFK is shown in ribbon format. The myosin heavy chain is depicted in blue, the essential light chain in red and the regulatory light chain in green.

Figure 3.

Bar diagrams of the heavy chains of the human myosin superfamily. A representative myosin from each class found in humans is shown. The various functional domains are color‐coded and are drawn approximately to scale.



Bahler M (2000) Are class III and class IX myosins motorized signalling molecules? Biochimica et Biophysica Acta 1496: 52–59.

Barylko B, Binns DD and Albanesi JP (2000) Regulation of the enzymatic and motor activities of myosin I. Biochimica et Biophysica Acta 1496: 23–35.

Berg JS and Cheney RE (2002) Myosin‐X is an unconventional myosin that undergoes intrafilopodial motility. Nature Cell Biology 4: 246–250.

Berg JS, Powell BC and Cheney RE (2001) A millennial myosin census. Molecular Biology of the Cell 12: 780–794.

Buss F, Arden SD, Lindsay M, Luzio JP and Kendrick‐Jones J (2001) Myosin VI isoform localized to clathrin‐coated vesicles with a role in clathrin‐mediated endocytosis. EMBO Journal 20: 3676–3684.

Friedman TB, Sellers JR and Avraham KB (1999) Unconventional myosins and the genetics of hearing loss. American Journal of Medical Genetics 89: 147–157.

Heath KE, Campos‐Barros A, Toren A, et al. (2001) Nonmuscle myosin heavy chain IIA mutations define a spectrum of autosomal dominant macrothrombocytopenias: May–Hegglin anomaly and Fechtner, Sebastian, Epstein, and Alport‐like syndromes. American Journal of Human Genetics 69: 1033–1045.

Holt JR, Gillespie SK, Provance DW, et al. (2002) A chemical‐genetic strategy implicates myosin‐1c in adaptation by hair cells. Cell 108: 371–381.

Howard J (1997) Molecular motors: structural adaptations to cellular functions. Nature 389: 561–567.

Marian AJ and Roberts R (2001) The molecular genetic basis for hypertrophic cardiomyopathy. Journal of Molecular and Cellular Cardiology 33: 655–670.

Mehta A (2001) Myosin learns to walk. Journal of Cell Science 114: 1981–1998.

Reck‐Peterson SL, Provance Jr DW, Mooseker MS and Mercer JA (2000) Class V myosins. Biochimica et Biophysica Acta 1496: 36–51.

Sellers JR (1999) Protein Profile: Myosins, 2nd edn. Oxford, UK: Oxford University Press.

Wells AL, Lin AW, Chen LQ, et al. (1999) Myosin VI is an actin‐based motor that moves backwards. Nature 401: 505–508.

Further Reading

El‐Amraoui A, Schonn JS, Kussel‐Andermann P, et al. (2002) MyRIP, a novel Rab effector, enables myosin VIIa recruitment to retinal melanosomes. The EMBO Journal 3: 463–470.

Homma K, Yoshimura M, Saito J, Ikebe R and Ikebe M (2001) The core of the motor domain determines the direction of myosin movement. Nature 412: 831–834.

Oliver TN, Berg JS and Cheney RE (1999) Tails of unconventional myosins. Cellular and Molecular Life Sciences 56: 243–257.

Spudich JA (2001) The myosin swinging cross‐bridge model. Nature Reviews Molecular Cell Biology 2: 387–392.

Uren D, Hwang HK, Hara Y, et al. (2000) Gene dosage affects the cardiac and brain phenotype in nonmuscle myosin II‐B‐depleted mice. Journal of Clinical Investigation 105: 663–671.

Wu XS, Rao K, Zhang H, et al. (2002) Identification of an organelle receptor for myosin‐Va. Nature Cell Biology 4: 271–278.

Web Links

myosin, heavy polypeptide 7, cardiac muscle, β (MYH7); LocusID: 4625. LocusLink:

myosin IIIA (MYO3A); LocusID: 53904. LocusLink:

myosin VA (MYO5A); LocusID: 4644. LocusLink:

myosin VIIA (MYO7A); LocusID: 4647. LocusLink:

myosin XVA (MYO15A); LocusID: 51168. LocusLink:

myosin, heavy polypeptide 7, cardiac muscle, β (MYH7); MIM number: 160760. OMIM:‐post/Omim/dispmim?160760

myosin IIIA (MYO3A); MIM number: 606808. OMIM:‐post/Omim/dispmim?606808

myosin VA (MYO5A); MIM number: 160777. OMIM:‐post/Omim/dispmim?160777

myosin VIIA (MYO7A); MIM number: 276903. OMIM:‐post/Omim/dispmim?276903

myosin XVA (MYO15A); MIM number: 602666. OMIM:‐post/Omim/dispmim?602666

Human Genome Organization (HUGO)

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Sellers, James R(Sep 2006) Myosins. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0006149]