The marked pH dependence of the talin-actin interaction.

The effect of pH on the interaction between talin and actin was examined by using cosedimentation assays, low shear viscometry, and electron microscopy. When the pH at which the interaction was tested was lowered from 7.5 to 7.0 and below, the ability of talin to cosediment with F-actin was greatly enhanced, with maximal binding at pH 6.6. Talin's ability to increase the low shear viscosity of F-actin solutions was also significantly elevated as pH was decreased from 7.4 to 6.6. Electron microscope observations of negatively stained actin controls and talin-actin mixtures supported these results by demonstrating an increase in the degree of crosslinking of actin filaments in the presence of talin at pH values of 7 and lower.