Salt dependent dimerisation of caldesmon

Abstract

Using analytical gel filtration (FPLC) we show here that avian gizzard caldesmon (chain molecular mass 150 kDa) self‐associates to form end‐to‐end dimers. Increasing salt concentration promotes dimerisation: at 150 mM KCl, about 40% of the caldesmon was dimeric. Freshly gel filtered caldesmon had an actin gelating activity which decreased with increasing ionic strength. At 150 mM KCl, caldesmon at a 1:90 molar ratio to actin doubled the low shear viscosity of F‐actin. Sixfold less filamin was required to produce the same effect.