“…The discovery (Busch et al, 1972), purification (Dayton, 1974;Dayton et al, 1976a) and characterization (Dayton ^ , 1975(Dayton ^ , , 1976a 2+ of a Ca -activated proteolytic enzyme (CAP) that very quickly removes Z-disks but that has very limited and specific effects on the myofibrillar proteins permitted some studies using this protease as a molecular probe of Z-disk architecture. The results of these experiments were very surprising and may have important consequences for ideas aborir the a-actinin/F-actin Interaction and Z-disk structure.…”