Subfragment

Rayment, 1., et al. Three-dimensional structure of myosin subfragment-1 a molecular motor. Science 261 5-58, 1996. 

Myosin Subfragment-1 Interacts With Two G-Actin Molecules... 

Combeau, C., Didry, D., Carlier. M.-F. (1992). Interaction between G-actin and myosin subfragment-I probed by covalent crosslinking. J. Biol. Chem. 267, 14038-14046. 

Fievez, S. Carlier, M.-F. (1993). Conformational changes in subdomain-2 of G-actin upon polymerization into F-actin and upon binding myosin subfragment-1. FEES Lett. 316, 186-190. 

Miller, L., Phillips, M Reisler, E. (1988). Polymerization of G-actin by myosin subfragment-1. J. Biol. Chem. 263, 1996-2002. 

Figure 14. Crystal structures of actin and myosin subfragment-1, shown to the same scale.

Heavy meromyosin (HMM molecular mass about 340 kDa) is a soluble protein that has both a fibrous portion and a globular portion (Figure 49-4). It exhibits ATPase activity and binds to F-actin. Digestion of HMM with papain generates two subfragments, S-1 and S-2. The S-2 fragment is fibrous in character, has no ATPase activity, and does not bind to F-actin. 

Miki M, Dosremedios CG (1988) Fluorescence quenching studies of fluorescein attached to Lys-61 or Cys-374 in actin effects of polymerization, myosin subfragment-1 binding, and tropomyosin-troponin binding. J Biochem Tokyo 104 232-235... 

Iodoacetyl-LC-biotin has been used to localize the SH thiol of myosin by use of an avidin-biotin complex visualized by electron microscopy (Sutoh et al., 1984) and to determine the spatial relationship between SHj and the actin binding site on the myosin subfragment-1 surface (Yamamoto et al., 1984). 

Aguirre, R., Gonsoulin, F., and Cheung, H.C. (1986) Interaction of fluorescently labelled myosin subfragment 1 with nucleotide and actin. Biochemistry 25, 6827. 

Greene, L.E. (1986) Cooperative binding of myosin subfragment one to regulated acdn as measured by fluoresce changes of troponin 1 modified within different fluorophores./. Biol. Chem. 261, 1279. 

Labbe, J.R, Mornet, D., Roseau, G., and Kassab, R. (1982) Cross-linking of F-actin to skeletal muscle myosin subfragment 1 with bis(imido esters) Further evidence for the interaction of myosin-head heavy chain with an actin dimer. Biochemistry 21, 6897-6902. 

Sutoh, K., and Hiratsuka, T. (1988) Spatial proximity of the glycine-rich loop and the SH2 thiol in myosin subfragment 1. Biochemistry 27(8), 2964-2969. 

Wells, J.A., Knoeber, C., Sheldon, M.C., Werber, M.M., and Yount, R.G. (1980) Cross-linking of myosin subfragment 1. Nucleotide-enhanced modification by a variety of bifunctional reagents./. Biol. Chem. 255, 11135. 

Yamamoto, K., Sekine, T., and Sutoh, K. (1984) Spatial relationship between SHI and the actin binding site on myosin subfragment-1 surface. FEES Lett. 176, 75-78. 

The XXYY group MO s can be constructed from the group MO s of the subfragments XY and XY taken in the appropriate geometry. 

Figure 4.5. Structure of myosin. Myosin comprises both light and heavy chains. The heavy chains may be cleaved by trypsin to generate light meromyosin (LMM) and heavy mero-myosin (HMM). Papain digestion of HMM yields subfragments SI and S2 each SI fragment contains an ATPase site and an actin-binding site. The light chains modify the activity of the ATPase.

White et aP measured the rates of phosphate release during a single turnover of actomyosin nucleoside triphosphate (NTP) hydrolysis using a double-mixing stopped-flow spectrofluorometer, at very low ionic strength to increase the affinity of myosin-ATP and myo-sin-ADP-Pi to actin. Myosin subfragment 1 and a series of nucleoside triphosphates were mixed and incubated for approximately 1-10 s to allow NTP to bind to myosin and generate a steady-state mixture of myosin-NTP and myosin-NDP-Pi. The steady-state intermediates were then mixed with actin. 

Figure 19-15 Ribbon representation of chicken skeletal myosin subfragment-1 showing the major domains and tryptic fragments. Prepared with the program MolScript. From Rayment.157...

---