EXAMINING F-ACTIN INTERACTION WITH INTACT TALIN AND TALIN HEAD AND TAIL FRAGMENT USING STATIC AND DYNAMIC LIGHT-SCATTERING

We examined the binding kinetics of intact talin and talin head and ta il fragment with F-actin at pH 7.0 and at low ionic strength. We obser ved by a transient kinetic method a fast followed by a slower binding process for intact talin and talin tail fragment with filamentous acti n. The latter can be attributed to F-actin cross-linking and/or bundli ng, which was observed in cosedimentation assays as well as by low she ar viscometry and electron microscopy [Zhang, J., Robson, R. M., Schmi dt, J. M. & Stromer, M. H. (1996) Biochem. Biophys. Res. Commun. 218, 530-537]. This finding is supported by dynamic light scattering measur ements, indicating changes in internal actin filament dynamics due to cross-linking/bundling events with intact talin and talin tail fragmen t. No binding of the talin head fragment with F-actin was detected by either method.