In the presence of Mg2+, the formation of actin filaments is hindered by glyceraldehyde-3-phosphate dehydrogenase. This effect, which increases with the square of Mg2+ concentration, is counteracted by 0.15 M KCl. Thus KCl, at concentrations found in the intracellular compartment, appears to be strictly required for the correct formation of actin filaments in all tissues in which the glyceraldehyde-phosphate dehydrogenase concentration is high.
Miguel Ángel Hernández Fuentes