Isolation and characterization of a 34,000-dalton calmodulin- and F-actin-binding protein from chicken gizzard smooth muscle.

We isolated a 34,000-dalton protein from the heat-soluble fraction of avian smooth muscle using the procedures of ammonium sulfate fractionation, cation exchange chromatography and gel filtration. The amount of 34,000-dalton protein in the muscle homogenate was as much as tropomyosin. The 34,000-dalton protein bound to F-actin and F-actin-tropomyosin in a Ca2+-independent manner, but it Ca2+-dependently interacted with calmodulin. We tentatively named the 34,000-dalton protein gizzard p34K.