The structure of F-actin and of actin filaments isolated from muscle

Invertebrate muscles: Thin and thick filament structure; molecular basis of contraction and its regulation, catch and asynchronous muscle

“…Although there was early controversy over repeat distances and numbers of actin monomers per repeat, biochemical, X-ray, and electron microscopy work indicates that nematode (Rosenbluth, 1967), crustacea Maéda et al, 1979;Namba et al, 1980;Wray and Holmes, 1981), insect flight muscle (Hanson and Lowy, 1963;Rayns, 1972;Reedy et al, 1983b;Ruiz et al, 1998;Cammarato et al, 2004), mollusc (Bear, 1945;Selby and Bear, 1956;Worthington, 1959;Hanson and Lowy, 1963;Hanson, 1967;Lowy and Vibert, 1967;Tsuchiya et al, 1977a,b;Vibert and Craig, 1982;Egelman et al, 1983), sea urchin (Obinata et al, 1974), and annelid (Bear, 1945;Hanson and Lowy, 1963) thin filaments are very similar to vertebrate thin filaments, with the double helix repeating once every 35-40 nm in 13-15 monomers (if the fact that the two monomers in question are from different strands is ignored; Fig. 1A).…”

Multiple tropomyosin polypeptides in chicken embryo fibroblasts: differential repression of transcription by Rous sarcoma virus transformation.

“…Analysis of cellular mRNA and runoff nuclear transcription experiments indicate that the repression of tropomyosin synthesis by Rous sarcoma virus transformation occurs at the level of transcription. This repression of tropomyosin synthesis is partially mimicked in normal chicken embryo fibroblasts during incubation in high-NaCI medium, a condition in which chicken embryo fibroblasts acquire many characteristics of transformed cells.Tropomyosin (TM) is a protein which has been best studied in skeletal muscle, where it is associated with actin in thin filaments and, together with the troponin complex, is responsible for mediating the effect of calcium on the contraction-generating interaction of actin and myosin (11,24). In nonmuscle cells (which do not contain troponin), TM is associated with actin in microfilaments (28,36,50) and, although the function of TM in these filaments is not known, there is evidence suggesting that one function resides in its ability to stabilize F-actin polymers (3,13).…”

“…Tropomyosin (TM) is a protein which has been best studied in skeletal muscle, where it is associated with actin in thin filaments and, together with the troponin complex, is responsible for mediating the effect of calcium on the contraction-generating interaction of actin and myosin (11,24). In nonmuscle cells (which do not contain troponin), TM is associated with actin in microfilaments (28,36,50) and, although the function of TM in these filaments is not known, there is evidence suggesting that one function resides in its ability to stabilize F-actin polymers (3,13).…”

Localization of [alpha]-actinin and tropomyosin in muscle and nonmuscle systems

“…Electron microscope studies (Hanson and Lowy, 1963;Moore _et _a].., 1970) have shown that the structure of purified fibrous actin, which is com pletely resistant to CAF degradation, is identical to the structure of fibrous actin in the thin filaments of striated muscle. It may seem surprising that an actin structure energetically stable in the thin filament is also not energetically the favored structure of any actin that may exist in the Z-disk.…”