A Rapid Purification of Alpha-actinin, Filamin, and a 130,000-dalton Protein from Smooth Muscle

Brief, low ionic strength extraction of chicken gizzard at 37 degrees C yields a solution containing a limited number of proteins including alpha-actinin, filamin, actin, desmin, and a 130,000-dalton polypeptide. The proteins are then fractionated by Mg2+- and (NH4)2SO4-induced precipitations and by ion exchange and gel filtration column chromatography to give rise to highly purified preparations of alpha-actinin, filamin, and a 130,000-dalton protein. The alpha-actinin and filamin isolated by this scheme are "native" based upon their S20,w values and their ability to bind to F-actin. These procedures, with minor modification, can be used for the purification of alpha-actinin from skeletal muscle and non-muscle tissues as well as for the purification of filamin from non-muscle tissue.