Thin Filament Regulation

Squire, J. M., and Morris, E. P. (1998). A new look at thin filament regulation in vertebrate skeletal muscle. FASEB/. 12, 761-771. 

Fig. 8. (A) Schematic of the three states of thin filament regulation. Surface view...

Cohen, C. (1983). Structural and dynamic aspects of thin filament regulation. In Biological structures and coupled flows (A. Oplatka and M. Balaban, Eds.), pp. 181-205. Academic Press, New York. 

There is an additional controlling pathway which is thin filament regulated this is dependent upon another protein, caldesmon, which is closely associated with the actin/tropomyosin-myosin domain. Caldesmon derives its name fi-om its intrinsic ability to bind to calmodulin with a much greater affinity than to the thin... 

The second aspect of the force-RLC phosphorylation relation that suggests additional regulation is illustrated by alterations in the slope of the relation (Fig. 1, lower right). Alterations in isometric force at fixed values of RLC phosphorylation are probably the strongest evidence for the in vivo operation of thin filament regulation. Smooth muscle contains two thin filament proteins, caldesmon and calponin, that inhibit actin-activated MgATPase activity of phosphorylated myosin. This inhibitory activity is reversed by the binding of Ca +ZCaM or by phosphorylation, and thus CD and CP may modulate the RLC phosphorylation... 

Major component of the thin filaments. Actin is an impotant cytoskeletal protein in non-muscle cells. Six human isoforms are known Cross-links actin at the Z disks Caps the plus ends of actin filaments at the Z-disk Thin filament regulation in smooth muscle... 

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