Actin Paracrystals Display Double Schottky Diode-Like Electrical Behavior

Actin filaments are abundant intracellular polymers implicated in cell motility and contraction. Actin also forms paracrystalline structures under various conditions, including exposure to lanthanides and other high ionic strength conditions. Here the electrical properties of purified actin paracrystals induced by either MgCl2 or GdCl3 are tested. Tight electrically seal-voltage-clamped crystals display strong rectification with a nonlinear conductance under symmetrical and biionic conditions, including 20 mm GdCl3/140 mm KCl and 10 mm MgCl2/140 mm KCl. Rectification is observed in symmetrical ionic conditions with positive-to-negative conductance ratios ranging from 4.18 to 9.00 nS. The current-to-voltage relationships can be fitted with theoretical double Schottky equations and resemble the behavior of semiconducting nanotubes. The highly nonlinear electrical properties of paracrystalline actin arrays may help explain the physiology of actin-rich cellular compartments, such as stereocilia of the cochlea and neuronal dendritic spines also suggest potentially relevant nano-technological properties of this protein. Actin is an abundant intracellular protein that forms paracrystalline structures. Here the electrical properties of purified actin paracrystals induced by incubation with either MgCl2 or GdCl3 are tested. Voltage-clamped crystals display strong rectification. The current-to-voltage relationships can be fitted with theoretical double Schottky equations and resemble the behavior of semiconducting nanotubes, suggesting potentially relevant nano-technological properties of this protein.image