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Gene Review

MYO2  -  myosin 2

Saccharomyces cerevisiae S288c

Synonyms: CDC66, Cell division control protein 66, Class V unconventional myosin MYO2, Myosin V MYO2, Myosin-2, ...
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High impact information on MYO2


Biological context of MYO2

  • Alterations of MYO4 or MYO2 indicate that neither the motor domains nor tails of these myosins are required to confer the overexpression phenotype, whereas the neck region may be required [5].
  • However, overexpression of MYO4 or MYO2 results in several morphological abnormalities, including the formation of short strings of unseparated cells in diploid strains, or clusters of cells in haploid strains [5].
  • The data support a model in which the Myo2p tail tethers secretory vesicles, and the motor transports them down polarized actin cables to the site of exocytosis [6].
  • In contrast, a different point mutation, mlc1-11, displayed defects in cytokinesis and in interactions with Myo2p and Iqg1p [7].
  • The tail domain of Myo2p is sufficient for localization at low- expression levels and causes mislocalization of the endogenous Myo2p from sites of polarized cell growth [8].

Anatomical context of MYO2


Associations of MYO2 with chemical compounds

  • The Myo2p in this pellet is not solubilized by Mg++-ATP or Triton X-100, but is solubilized by high salt [8].
  • The wild-type MYO2 gene encodes an essential form of myosin composed of an NH2-terminal domain typical of the globular, actin-binding domain of other myosins [12].
  • Unexpectedly, we found that abolition of microtubules by nocodazole does not interfere with the ability of Smy1p to correct the mutant Myo2p defect, nor does it interfere with the ability of Smy1p to localize properly [13].
  • Myo2p motility is Ca(2+) insensitive [14].
  • Third, Myo2p coimmunoprecipitates with calmodulin in the presence of Ca2+ or EGTA [15].

Physical interactions of MYO2

  • Gel overlay assay shows that a mutant calmodulin with the F92A alteration has severely reduced binding affinity to a GST-Myo2p fusion protein [16].
  • Vac17p interacts with the Myo2p cargo-binding domain, but not with vacuole inheritance-defective myo2 mutants that have single amino acid changes within this region [17].
  • This suggests that Myo2p serves as a molecular motor for vacuole transport along actin filaments [18].
  • The crystal structures of Mlc1p bound to IQ2 and IQ4 of Myo2p differ dramatically [19].
  • We now show by two-hybrid analysis that a 69-amino acid region of the Smy1p tail interacts with the globular portion of the Myo2p tail [20].

Co-localisations of MYO2

  • Deletion of this myosin-binding region of Smy1p eliminates its ability to colocalize with Myo2p and to overcome the myo2-66 mutant defects, suggesting that the interaction is necessary for these functions [20].

Regulatory relationships of MYO2

  • We propose that Smy1p enhances some aspect of Myo2p function, perhaps delivery or docking of vesicles at the bud tip [20].

Other interactions of MYO2

  • We noted that the myo2 mutant can recover from osmotic shift (unlike actin mutants; Novick, P., and D. Botstein. 1985. Cell. 40:405-416) [10].
  • However, the lethality of MYO2 deletion is not overcome by SMY1 overexpression [10].
  • Reduced levels of MYO2 overcome the haploinsufficiency of MLC1 [21].
  • The myo2-66 conditional mutation shows synthetic lethality with the TPM1 disruption, indicating that the MYO2 and TPM1 gene products may be involved in the same, or parallel function [22].
  • A comparison with other myosins in GenBank reveals that Myo4 protein is most closely related to the yeast Myo2 protein, another class V myosin [5].

Analytical, diagnostic and therapeutic context of MYO2


  1. S. cerevisiae alpha pheromone receptors activate a novel signal transduction pathway for mating partner discrimination. Jackson, C.L., Konopka, J.B., Hartwell, L.H. Cell (1991) [Pubmed]
  2. Mechanisms of polarized growth and organelle segregation in yeast. Pruyne, D., Legesse-Miller, A., Gao, L., Dong, Y., Bretscher, A. Annu. Rev. Cell Dev. Biol. (2004) [Pubmed]
  3. Regulated degradation of a class V myosin receptor directs movement of the yeast vacuole. Tang, F., Kauffman, E.J., Novak, J.L., Nau, J.J., Catlett, N.L., Weisman, L.S. Nature (2003) [Pubmed]
  4. Myosin V orientates the mitotic spindle in yeast. Yin, H., Pruyne, D., Huffaker, T.C., Bretscher, A. Nature (2000) [Pubmed]
  5. Identification of MYO4, a second class V myosin gene in yeast. Haarer, B.K., Petzold, A., Lillie, S.H., Brown, S.S. J. Cell. Sci. (1994) [Pubmed]
  6. The COOH-terminal domain of Myo2p, a yeast myosin V, has a direct role in secretory vesicle targeting. Schott, D., Ho, J., Pruyne, D., Bretscher, A. J. Cell Biol. (1999) [Pubmed]
  7. Identification and functional analysis of the essential and regulatory light chains of the only type II myosin Myo1p in Saccharomyces cerevisiae. Luo, J., Vallen, E.A., Dravis, C., Tcheperegine, S.E., Drees, B., Bi, E. J. Cell Biol. (2004) [Pubmed]
  8. The tail of a yeast class V myosin, myo2p, functions as a localization domain. Reck-Peterson, S.L., Novick, P.J., Mooseker, M.S. Mol. Biol. Cell (1999) [Pubmed]
  9. A type V myosin (Myo2p) and a Rab-like G-protein (Ypt11p) are required for retention of newly inherited mitochondria in yeast cells during cell division. Boldogh, I.R., Ramcharan, S.L., Yang, H.C., Pon, L.A. Mol. Biol. Cell (2004) [Pubmed]
  10. Immunofluorescence localization of the unconventional myosin, Myo2p, and the putative kinesin-related protein, Smy1p, to the same regions of polarized growth in Saccharomyces cerevisiae. Lillie, S.H., Brown, S.S. J. Cell Biol. (1994) [Pubmed]
  11. The Peroxisomal Membrane Protein Inp2p Is the Peroxisome-Specific Receptor for the Myosin V Motor Myo2p of Saccharomyces cerevisiae. Fagarasanu, A., Fagarasanu, M., Eitzen, G.A., Aitchison, J.D., Rachubinski, R.A. Dev. Cell (2006) [Pubmed]
  12. The Saccharomyces cerevisiae MYO2 gene encodes an essential myosin for vectorial transport of vesicles. Johnston, G.C., Prendergast, J.A., Singer, R.A. J. Cell Biol. (1991) [Pubmed]
  13. Smy1p, a kinesin-related protein that does not require microtubules. Lillie, S.H., Brown, S.S. J. Cell Biol. (1998) [Pubmed]
  14. The yeast class V myosins, Myo2p and Myo4p, are nonprocessive actin-based motors. Reck-Peterson, S.L., Tyska, M.J., Novick, P.J., Mooseker, M.S. J. Cell Biol. (2001) [Pubmed]
  15. The unconventional myosin, Myo2p, is a calmodulin target at sites of cell growth in Saccharomyces cerevisiae. Brockerhoff, S.E., Stevens, R.C., Davis, T.N. J. Cell Biol. (1994) [Pubmed]
  16. Identification of functional connections between calmodulin and the yeast actin cytoskeleton. Sekiya-Kawasaki, M., Botstein, D., Ohya, Y. Genetics (1998) [Pubmed]
  17. Identification of an organelle-specific myosin V receptor. Ishikawa, K., Catlett, N.L., Novak, J.L., Tang, F., Nau, J.J., Weisman, L.S. J. Cell Biol. (2003) [Pubmed]
  18. Actin and myosin function in directed vacuole movement during cell division in Saccharomyces cerevisiae. Hill, K.L., Catlett, N.L., Weisman, L.S. J. Cell Biol. (1996) [Pubmed]
  19. Two distinct myosin light chain structures are induced by specific variations within the bound IQ motifs-functional implications. Terrak, M., Wu, G., Stafford, W.F., Lu, R.C., Dominguez, R. EMBO J. (2003) [Pubmed]
  20. The yeast kinesin-related protein Smy1p exerts its effects on the class V myosin Myo2p via a physical interaction. Beningo, K.A., Lillie, S.H., Brown, S.S. Mol. Biol. Cell (2000) [Pubmed]
  21. Mlc1p is a light chain for the unconventional myosin Myo2p in Saccharomyces cerevisiae. Stevens, R.C., Davis, T.N. J. Cell Biol. (1998) [Pubmed]
  22. Characterization of TPM1 disrupted yeast cells indicates an involvement of tropomyosin in directed vesicular transport. Liu, H., Bretscher, A. J. Cell Biol. (1992) [Pubmed]
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