Actin filaments representation

FIGURE 17.23 The mechanism of skeletal muscle contraction. The free energy of ATP hydrolysis drives a conformational change in the myosin head, resulting in net movement of the myosin heads along the actin filament. Inset) A ribbon and space-filling representation of the actin—myosin interaction. (SI myosin image courtesy of Ivan Rayment and Hazel M. Holden, University of Wiseonsin, Madison.)... 

Fig. 9. Representation of a 13/6 actin filament together with its illustration by means of a radial net. In (A) an imaginary piece of paper is wrapped round the filament and on it are marked all the positions of the actin monomers. The paper is then unwrapped as in (B) and the helical tracks in (A) become straight lines. The final result in (C) is the radial projection or radial net. The 59 A pitch length (P) and 27.5 A subunit axial translation (h) are indicated in (C).

Fig. 2 Schematic representation of the physiological and pathological functions of tau phosphorylation. When the phosphorylation state of tau is appropriately coordinated, it plays a role in regulating neuiite outgrowth, axonal transport, and microtubule stability and dynamics. However, in pathological conditions in which there is an imbalance in the phosphorylation/dephosphorylation of tau, aberrant tau phosphorylation can cause tau/actin filament formation, disrupt microtubule-based processes owing to decreased microtubule binding, and perhaps even increase cell death (modified from Johnson et al., 2004 (129))...

Fig. 3 Schematic representation of the multiple functional involvement of profilin at the plasma membrane. The ratio between membrane-bound and free profilin is regulated by the level of PIP2 and determines the complex formation of profilin with G-actin. Upon release from the membrane, profilin is involved in charging G-actin with ATP (center). Subsequently, the profilin-ATP-G-actin complex adds to nascent actin filaments and participates in the generation of actin filaments as needed for adhesion complexes Qeft) and lamellipodial actin networks (right). Details of this scenario show only selected examples of all possible constellations and are thus highly speculative, but consistent with the present knowledge...

Figure 8.45. (Top) Electron micrograph of a myofibril delineating the A and I bands, the Z disk, and the H zone. (Bottom) Schematic representation of a microfibril showing thin actin filaments emanating from Z disks and overlapping with thick myosin...

Figure 4.11 (a) Diagrammatic representation of the myosin filament and its interaction with the actin filament during the ATP hydrolysis cycle. More detail of the steps involved is given in section S.l. (b) Outline of the composition of the myosin molecule indicating the SI head of each chain, which contains both the active site for the ATPase reaction and the actin binding site. The proteolytic cleavage sites, a and b, are involved in the production SI and the double headed heavy meromyosin (HMM) respectively. 

Figure 49-3. Schematic representation of the thin fiiament, showing the spatiai configuration of its three major protein components actin, myosin, and tropomyosin. The upper panei shows individual molecules of G-actin. The middle panel shows actin monomers assembled into F-actin. Individual molecules of tropomyosin (two strands wound around one another) and of troponin (made up of its three subunits) are also shown. The lower panel shows the assembled thin filament, consisting of F-actin, tropomyosin, and the three subunits of troponin (TpC, Tpl, andTpT).

Fig. 16.2 Schematic representation of cellular and artificial membrane nanotubes. (A) Two cells are connected by a tunneling nanotube (arrowhead) containing a bundle of filamentous actin (red line). N (grey), nucleus M (purple), mitochondrium ER (green), endoplasmic reticulum G (blue), Golgi apparatus. (B) Lipid nanotube connecting two lipid vesicles formed by pulling a membrane tether. (C) Membrane tether pulled from the plasma membrane of a cell (see Color Plates)...

Fig. 5. Schematic representation of components of the thin filament of smooth muscle. Although calponin and caldesmon are both shown as components of the same filament, there is evidence that they may selectively associate with different actin isoforms in different populations of thin filaments...

Figure 4.4. Model of muscle contraction based on sliding filaments [ 2 ] (a) The bands H and I are shortened during contraction the length of thick and thin filaments remain constant the arrows indicate the myosin and actin-G polarity (b) Schematic representation of the interactions between myosin head and thin filaments during contraction.

---