Use of a chaotropic anion iodide in the purification of Z-line proteins: Isolation of CapZ from fish white muscle

In the present study, we have described an improved method allowing the iso lation of proteins which form tightly associated complexes in organized str uctures such as Z line in skeletal muscle. This procedure is based on both extraction and chromatography in the presence of a chaotropic agent. KI at medium concentration (0.6 M) was selected, taking into account its dissocia ting activity and mild effect on the native state of proteins. This procedu re was applied to purify and to characterize for the first time a CapZ from fish white muscle, a protein involved in the stabilization of the filament s in Z line. The alpha and beta CapZ subunits were identified using anti-sy nthetic peptide antibodies directed against conserved sequences derived fro m chicken CapZ. The protocol can be also used for the isolation of other mu scular proteins such as alpha-actinin and actin. Finally this technique may be utilized to obtain a good amount of capping protein which could be empl oyed in experiments of microfilament dynamics. (C) 1999 Academic Press.