Actin filaments regulation

Craig, R., and Lehman, W. (2002). The ultrastructural basis of actin filament regulation. Results Probl. Cell. Differ. 36, 149-169. 

In Drosophila, Fat functions as a tumor suppressor gene and dachsous is involved in thorax, leg, and wing development. Several human and mouse homologs have been identified. FAT1 regulates actin filaments, and the Fail knockout leads to defects in glomerular slit formation [3]. 

More than 50 proteins have been discovered in the cytosol of nonmuscle cells that bind to actin and affect the assembly and disassembly of actin filaments or the cross-linking of actin filaments with each other, with other filamentous components of the cytoskeleton, or with the plasma membrane. Collectively, these are known as actin-binding proteins (ABPs). Their mechanisms of actions are complex and are subject to regulation by specific binding affinities to actin and other molecules, cooperation or competition with other ABPs, local changes in the concentrations of ions in the cytosol, and physical forces (Way and Weeds, 1990). Classifications of ABPs have been proposed that are based on their site of binding to actin and on their molecular structure and function (Pollard and Cooper, 1986 Herrmann, 1989 Pollard et al., 1994). These include the following ... 

Pointed-end-capping proteins are acumentin (65 kD), spectrin (220-260 kD), and p-actinin (37 kD). They also regulate the length of actin filaments. 

Thus far, microtubules and actin filaments and their associated proteins have been discussed to advantage as independent cytoskeletal components. In actual fact, all of the components of the cytoskeleton (including intermediate filaments) are precisely integrated with one another (Langford, 1995), as well as with various cytoplasmic organelles, the nuclear membrane, the plasma membrane, and the extracellular matrix. In its totality the cytoskeleton subserves many coordinated and regulated functions in the cell ... 

Tilney, L.G., Bonder, E.M., Coluccio, L.M., Moosekar, M.S. (1983). Actin from Thyone sperm assembles on only one end of an actin filament A behavior regulated by profilin. J. Cell Biol. 97, 112-124. 

Nebulin From Z line along length of actin filaments May regulate assembly and length of actin filaments. 

Gallo, G. and Letourneau, P. C. Regulation of growth cone actin filaments by guidance cues. /. Neurobiol. 58 92-102, 2004. 

Umeda, M., and Emoto, K., 1999, Membrane phospholipid dynamics during cytokinesis regulation of actin filament assembly by redistribution of membrane surface phosphohpid. Chem. Phys. Lipids, 101 81-91. 

Tropomyosin is a long helical molecule (70 kDa) which extends along the long axis of the actin filament (Figure 13.7). Each tropomyosin molecule covers seven actin monomers and plays a central role in the regulation of muscle contraction. 

Contraction-relaxation processes in muscle proceed by a sliding filament mechanism, whereby actin and myosin filament move relative to one another. The reaction is energized by ATP and regulated by the level of calcium ions. In vertebrate skeletal muscle contraction is controlled by the interaction of calcium ions with the specific protein troponin which is attached to the actin filaments, whereas among many invertebrates troponin is lacking and myosin and not actin is controlled192. However, in a few invertebrates both types of filaments are involved in regulation. 

Barkalow, K., W. Witke, D.J. Kwiatkowski, and J.H. Hartwig. 1996. Coordinated regulation of platelet actin filament barbed ends by gelsolin and capping protein. J Cell Biol. 134 389-99. 

Yin, H.L., K.S. Zaner, and T.P. Stossel. 1980. Ca2+ control of actin gelation. Interaction of gelsolin with actin filaments and regulation of actin gelation. J Biol Chem. 255 9494-500. 

The muscle sarcomere contains the principal contractile proteins myosin and actin (Fig. 3A to C), which on their own can produce force and movement, together with a number of cytoskeletal and regulatory proteins. The latter include titin, C-protein (MyBP-C), tropomyosin, troponin, a-actinin, myomesin, M-protein, and so on. Some of these help to organize the myosin and actin filaments in the sarcomere, some to define the filament lengths and structure, some to regulate activity, and some to modulate the actin-myosin interaction when the muscle is active. 

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