This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
<table><tr><td colspan='2'>[[2w4a]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2W4A OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=2W4A FirstGlance]. <br>
+
<table><tr><td colspan='2'>[[2w4a]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2W4A OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2W4A FirstGlance]. <br>
[[http://www.uniprot.org/uniprot/MYSS_CHICK MYSS_CHICK]] Muscle contraction. Myosin is a protein that binds to F-actin and has ATPase activity that is activated by F-actin.
+
[https://www.uniprot.org/uniprot/MYL11_CHICK MYL11_CHICK] Myosin regulatory subunit that plays an essential to maintain muscle integrity during early development (By similarity). Plays a role in muscle contraction (PubMed:15256600).[UniProtKB:O93409]<ref>PMID:15256600</ref>
2w4a is a 3 chain structure with sequence from Gallus gallus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
MYL11_CHICK Myosin regulatory subunit that plays an essential to maintain muscle integrity during early development (By similarity). Plays a role in muscle contraction (PubMed:15256600).[UniProtKB:O93409][1]
Evolutionary Conservation
Checkto colour the structure by Evolutionary Conservation, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
BACKGROUND: Isometric muscle contraction, where force is generated without muscle shortening, is a molecular traffic jam in which the number of actin-attached motors is maximized and all states of motor action are trapped with consequently high heterogeneity. This heterogeneity is a major limitation to deciphering myosin conformational changes in situ. METHODOLOGY: We used multivariate data analysis to group repeat segments in electron tomograms of isometrically contracting insect flight muscle, mechanically monitored, rapidly frozen, freeze substituted, and thin sectioned. Improved resolution reveals the helical arrangement of F-actin subunits in the thin filament enabling an atomic model to be built into the thin filament density independent of the myosin. Actin-myosin attachments can now be assigned as weak or strong by their motor domain orientation relative to actin. Myosin attachments were quantified everywhere along the thin filament including troponin. Strong binding myosin attachments are found on only four F-actin subunits, the "target zone", situated exactly midway between successive troponin complexes. They show an axial lever arm range of 77 degrees /12.9 nm. The lever arm azimuthal range of strong binding attachments has a highly skewed, 127 degrees range compared with X-ray crystallographic structures. Two types of weak actin attachments are described. One type, found exclusively in the target zone, appears to represent pre-working-stroke intermediates. The other, which contacts tropomyosin rather than actin, is positioned M-ward of the target zone, i.e. the position toward which thin filaments slide during shortening. CONCLUSION: We present a model for the weak to strong transition in the myosin ATPase cycle that incorporates azimuthal movements of the motor domain on actin. Stress/strain in the S2 domain may explain azimuthal lever arm changes in the strong binding attachments. The results support previous conclusions that the weak attachments preceding force generation are very different from strong binding attachments.
Electron tomography of cryofixed, isometrically contracting insect flight muscle reveals novel actin-myosin interactions.,Wu S, Liu J, Reedy MC, Tregear RT, Winkler H, Franzini-Armstrong C, Sasaki H, Lucaveche C, Goldman YE, Reedy MK, Taylor KA PLoS One. 2010 Sep 9;5(9). pii: e12643. PMID:20844746[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Sherwood JJ, Waller GS, Warshaw DM, Lowey S. A point mutation in the regulatory light chain reduces the step size of skeletal muscle myosin. Proc Natl Acad Sci U S A. 2004 Jul 27;101(30):10973-8. PMID:15256600 doi:10.1073/pnas.0401699101
↑ Wu S, Liu J, Reedy MC, Tregear RT, Winkler H, Franzini-Armstrong C, Sasaki H, Lucaveche C, Goldman YE, Reedy MK, Taylor KA. Electron tomography of cryofixed, isometrically contracting insect flight muscle reveals novel actin-myosin interactions. PLoS One. 2010 Sep 9;5(9). pii: e12643. PMID:20844746 doi:10.1371/journal.pone.0012643
