Filaments, thin calcium regulation

Calmodulin is a prime candidate for the role of the Ca2+-sensitizing protein since it is the most abundant calcium binding protein in smooth muscles, with a total concentration in the same range as CD. Under particular reaction conditions (37°C/120 mM KCl), Ca " -regulated synthetic thin filaments may be reconstituted using only actin, TM, CD, and CM. In contrast, native thin filaments are Ca + sensitive over a wide range of conditions and in conditions optimal for Ca + sensitivity in native thin filaments, the synthetic thin filaments are usually completely Ca + insensitive (Smith et al., 1987 Pritchard and Marston, 1989 Marston et al., 1988a). 

---