MYO2/YOR326W Summary Help

Standard Name MYO2 1, 2
Systematic Name YOR326W
Alias CDC66 3
Feature Type ORF, Verified
Description Type V myosin motor involved in actin-based transport of cargos; required for the polarized delivery of secretory vesicles, the vacuole, late Golgi elements, peroxisomes, and the mitotic spindle; MYO2 has a paralog, MYO4, that arose from the whole genome duplication (4, 5 and see Summary Paragraph)
Name Description MYOsin 6
Chromosomal Location
ChrXV:925721 to 930445 | ORF Map | GBrowse
Genetic position: 174 cM
Gene Ontology Annotations All MYO2 GO evidence and references
  View Computational GO annotations for MYO2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 8 genes
Classical genetics
reduction of function
Large-scale survey
reduction of function
434 total interaction(s) for 208 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 71
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 42
  • Co-crystal Structure: 4
  • Co-fractionation: 2
  • Co-localization: 2
  • Far Western: 1
  • FRET: 1
  • PCA: 3
  • Protein-peptide: 2
  • Reconstituted Complex: 23
  • Two-hybrid: 58

Genetic Interactions
  • Dosage Growth Defect: 7
  • Dosage Lethality: 6
  • Dosage Rescue: 18
  • Negative Genetic: 79
  • Phenotypic Enhancement: 7
  • Positive Genetic: 5
  • Synthetic Growth Defect: 19
  • Synthetic Lethality: 74
  • Synthetic Rescue: 8

Expression Summary
Length (a.a.) 1,574
Molecular Weight (Da) 180,679
Isoelectric Point (pI) 6.26
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXV:925721 to 930445 | ORF Map | GBrowse
Genetic position: 174 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..4725 925721..930445 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000005853

MYO2 encodes an essential class V myosin heavy chain and MYO4 encodes a second, non-essential, class V myosin (6, 7, 8, 9). Class V myosins are usually homodimers and function as molecular motors that in yeast transport distinct sets of cargo to polarized regions of the cell along actin cables (10, 4). Myo2p predominantly transports membrane-bound organelles, whereas Myo4p moves mRNAs (see below and MYO4). Through evolution Myo4p has lost features found in Myo2p and animal myosins, such as portions of the tail region required for the transport of membrane-bound organelles (10, 11). Still, Myo2p and Myo4p are more closely related to each other than any other myosin. Non-yeast homologs of MYO2 and MYO4 include the mouse dilute gene, chick brain M5a, and the human MYO5A (OMIM), which is mutant in some patients with Griscelli syndrome (10).

Class V myosins have a particular domain architecture and distinct modes of regulation. Myo2p and Myo4p have an N-teminal actin-binding motor domain and a globular C-terminal tail domain separated by a coiled-coil dimerization domain (10). C-terminal to the motor domain is a neck region that contains six IQ motifs that can bind calmodulin encoded by CMD1 (10, 12). Myosins are typically regulated by interactions with light chains. The myosin light chain encoded by MLC1 physically interacts with, and regulates Myo2p (13). The binding of the Myo2p tail by the kinesin-like protein Smy1p promotes the polarized localization of Myo2p and impacts Myo2p function (14, 11, 15, 16). While the light chain(s) that regulate Myo4p are yet to be defined, a novel motor-binding protein, She4p, may modulate Myo4p function (17). Myo2p is phosphorylated in vivo and the functional consequences of these modifications are complex (18).

Myo2p promotes polarized growth by mediating the vectorial transport of organelles along actin cables to sites such as the growing bud during vegetative growth (4), the bud neck during cytokinesis (19), and the shmoo tip during mating (20, 21, 22). Organelles transported into the growing bud include secretory vesicles (6, 23, 24, 11, 25), vacuoles (26), peroxisomes (27), and late-Golgi elements (28). Myo2p also participates in orientation of the mitotic spindle early in the cell cycle (22). Cargo-specific myosin receptors act as links between the cargo and the myosin tail. Myosin receptors include Vac8p-Vac17p on vacuoles (29) and Inp2p on peroxisomes (30). Sec4p, a vesicle-bound rab, associates with Myo2p, and along with Sec2p and Smy1p, is critical for vesicle transport (4). Myo2p participates in spindle orientation by actively transporting Kar9p/Bim1p-decorated microtubule ends into the bud (4). The role of type V myosins in mitochondrial inheritance has been controversial. There is no dispute that actin is required for this process. Early studies suggested that type V myosins are dispensible for this process (31) and demonstrated that the force used for directed mitochondrial movement is generated by Arp2/3-dependent actin nucleation (32). Others have suggested that Myo2p is involved in mitochondrial inheritance (33, 34). A more recent study attempts to reconcile the differences and provides evidence that Myo2p and the rab Ypt11p are required for the retention of newly inherited mitochondria in the bud (35).

Last updated: 2006-10-30 Contact SGD

References cited on this page View Complete Literature Guide for MYO2
1) Hanic-Joyce, P. and Carruthers, D.R.  (1985) Personal Communication, Mortimer Map Edition 9
2) Singer, R.  (1992) Personal Communication, Mortimer Map Edition 11
3) Prendergast JA, et al.  (1990) Size selection identifies new genes that regulate Saccharomyces cerevisiae cell proliferation. Genetics 124(1):81-90
4) Pruyne D, et al.  (2004) Mechanisms of polarized growth and organelle segregation in yeast. Annu Rev Cell Dev Biol 20:559-91
5) Byrne KP and Wolfe KH  (2005) The Yeast Gene Order Browser: combining curated homology and syntenic context reveals gene fate in polyploid species. Genome Res 15(10):1456-61
6) Johnston GC, et al.  (1991) The Saccharomyces cerevisiae MYO2 gene encodes an essential myosin for vectorial transport of vesicles. J Cell Biol 113(3):539-51
7) Haarer BK, et al.  (1994) Identification of MYO4, a second class V myosin gene in yeast. J Cell Sci 107 ( Pt 4)():1055-64
8) Espreafico EM, et al.  (1992) Primary structure and cellular localization of chicken brain myosin-V (p190), an unconventional myosin with calmodulin light chains. J Cell Biol 119(6):1541-57
9) Brown SS  (1997) Myosins in yeast. Curr Opin Cell Biol 9(1):44-8
10) Mermall V, et al.  (1998) Unconventional myosins in cell movement, membrane traffic, and signal transduction. Science 279(5350):527-33
11) Schott D, et al.  (1999) The COOH-terminal domain of Myo2p, a yeast myosin V, has a direct role in secretory vesicle targeting. J Cell Biol 147(4):791-808
12) Brockerhoff SE, et al.  (1994) The unconventional myosin, Myo2p, is a calmodulin target at sites of cell growth in Saccharomyces cerevisiae. J Cell Biol 124(3):315-23
13) Stevens RC and Davis TN  (1998) Mlc1p is a light chain for the unconventional myosin Myo2p in Saccharomyces cerevisiae. J Cell Biol 142(3):711-22
14) Lillie SH and Brown SS  (1994) Immunofluorescence localization of the unconventional myosin, Myo2p, and the putative kinesin-related protein, Smy1p, to the same regions of polarized growth in Saccharomyces cerevisiae. J Cell Biol 125(4):825-42
15) Beningo KA, et al.  (2000) The yeast kinesin-related protein Smy1p exerts its effects on the class V myosin Myo2p via a physical interaction. Mol Biol Cell 11(2):691-702
16) Pashkova N, et al.  (2005) A point mutation in the cargo-binding domain of myosin V affects its interaction with multiple cargoes. Eukaryot Cell 4(4):787-98
17) Wesche S, et al.  (2003) The UCS domain protein She4p binds to myosin motor domains and is essential for class I and class V myosin function. Curr Biol 13(9):715-24
18) Legesse-Miller A, et al.  (2006) Regulated phosphorylation of budding yeast's essential myosin V heavy chain, Myo2p. Mol Biol Cell 17(4):1812-21
19) Wagner W, et al.  (2002) Mlc1p promotes septum closure during cytokinesis via the IQ motifs of the vesicle motor Myo2p. EMBO J 21(23):6397-408
20) Jackson CL, et al.  (1991) S. cerevisiae alpha pheromone receptors activate a novel signal transduction pathway for mating partner discrimination. Cell 67(2):389-402
21) Catlett NL and Weisman LS  (1998) The terminal tail region of a yeast myosin-V mediates its attachment to vacuole membranes and sites of polarized growth. Proc Natl Acad Sci U S A 95(25):14799-804
22) Hwang E, et al.  (2003) Spindle orientation in Saccharomyces cerevisiae depends on the transport of microtubule ends along polarized actin cables. J Cell Biol 161(3):483-8
23) Govindan B, et al.  (1995) The role of Myo2, a yeast class V myosin, in vesicular transport. J Cell Biol 128(6):1055-68
24) Pruyne DW, et al.  (1998) Tropomyosin-containing actin cables direct the Myo2p-dependent polarized delivery of secretory vesicles in budding yeast. J Cell Biol 143(7):1931-45
25) Schott DH, et al.  (2002) Secretory vesicle transport velocity in living cells depends on the myosin-V lever arm length. J Cell Biol 156(1):35-9
26) Catlett NL, et al.  (2000) Two distinct regions in a yeast myosin-V tail domain are required for the movement of different cargoes. J Cell Biol 150(3):513-26
27) Hoepfner D, et al.  (2001) A role for Vps1p, actin, and the Myo2p motor in peroxisome abundance and inheritance in Saccharomyces cerevisiae. J Cell Biol 155(6):979-90
28) Rossanese OW, et al.  (2001) A role for actin, Cdc1p, and Myo2p in the inheritance of late Golgi elements in Saccharomyces cerevisiae. J Cell Biol 153(1):47-62
29) Ishikawa K, et al.  (2003) Identification of an organelle-specific myosin V receptor. J Cell Biol 160(6):887-97
30) Fagarasanu A, et al.  (2006) The peroxisomal membrane protein Inp2p is the peroxisome-specific receptor for the myosin V motor Myo2p of Saccharomyces cerevisiae. Dev Cell 10(5):587-600
31) Simon VR, et al.  (1995) Actin-dependent mitochondrial motility in mitotic yeast and cell-free systems: identification of a motor activity on the mitochondrial surface. J Cell Biol 130(2):345-54
32) Boldogh IR, et al.  (2001) Arp2/3 complex and actin dynamics are required for actin-based mitochondrial motility in yeast. Proc Natl Acad Sci U S A 98(6):3162-7
33) Itoh T, et al.  (2002) Complex formation with Ypt11p, a rab-type small GTPase, is essential to facilitate the function of Myo2p, a class V myosin, in mitochondrial distribution in Saccharomyces cerevisiae. Mol Cell Biol 22(22):7744-57
34) Itoh T, et al.  (2004) Mmr1p is a mitochondrial factor for Myo2p-dependent inheritance of mitochondria in the budding yeast. EMBO J 23(13):2520-30
35) Boldogh IR, et al.  (2004) 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. Mol Biol Cell 15(9):3994-4002