Final Version edit
Myosin V
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.
ADDITION
The Myosin V motor head can be subdivided into the following functional regions:[1]
- Nucleotide-binding site - These elements together coordinate di-valent metal cations (usually magnesium) and catalyze hydrolysis:
- Switch I - This contains a highly conserved SSR motif. Isomerizes in the presence of ATP.
- Switch II - This is the Kinase-GTPase version of the Walker B motif DxxG. Isomerizes in the presence of ATP.
- P-loop - This contains the Walker A motif GxxxxGK(S,T). This is the primary ATP binding site.
- Transducer - The seven β-strands that underpin the motor head's structure.[2]
- U50 and L50 - The Upper (U50) and Lower (L50) domains are each around 50kDa. Their spatial separation[3] forms a cleft critical for binding to actin and some regulatory compounds.
- SH1 helix and Relay - These elements together provide an essential mechanism for coupling the enzymatic state of the motor domain to the powerstroke-producing region (converter domain, lever arm, and light chains).[4][5]
- Converter - This converts a change of conformation in the motor head to an angular displacement of the lever arm (in most cases reinforced with light chains).[5]
EXPLANATION
Added a substantial amount of information regarding the Myosin V motor head. The edit begins “The Myosin V motor head can be subdivided into the following functional regions:” and then proceeds to provide information on some of the more interesting (and general to other motor heads) regions of the Myosin V motor head. Added references and links to other Wikipedia pages to support the addition. ~~~~Tannerhoole
References edit
- ^ a b Sweeney, H. Lee; Houdusse, Anne (2010-04-01). "Structural and Functional Insights into the Myosin Motor Mechanism". Annual Review of Biophysics. 39 (1): 539–557. doi:10.1146/annurev.biophys.050708.133751. ISSN 1936-122X.
- ^ Kull, F. J.; Vale, R. D.; Fletterick, R. J. (1998-11-19). "The case for a common ancestor: kinesin and myosin motor proteins and G proteins". Journal of Muscle Research and Cell Motility. 19 (8): 877–886. doi:10.1023/a:1005489907021. ISSN 0142-4319. PMID 10047987.
- ^ Sasaki, Naoya; Ohkura, Reiko; Sutoh, Kazuo (2000-12-08). "Insertion or Deletion of a Single Residue in the Strut Sequence of Dictyostelium Myosin II Abolishes Strong Binding to Actin *". Journal of Biological Chemistry. 275 (49): 38705–38709. doi:10.1074/jbc.M001966200. ISSN 0021-9258. PMID 11005804.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Shibata, Kotomi; Koyama, Tsubasa; Inde, Shohei; Iwai, Sosuke; Chaen, Shigeru (2017). "Mutations in the SH1 helix alter the thermal properties of myosin II". Biophysics and Physicobiology. 14 (0): 67–73. doi:10.2142/biophysico.14.0_67. ISSN 2189-4779. PMC 5468464. PMID 28630813.
{{cite journal}}: CS1 maint: PMC format (link) - ^ a b Kodera, Noriyuki; Ando, Toshio (2014-06-18). "The path to visualization of walking myosin V by high-speed atomic force microscopy". Biophysical Reviews. 6 (3–4): 237–260. doi:10.1007/s12551-014-0141-7. ISSN 1867-2450. PMC 4256461. PMID 25505494.