The Z-band: 85,000-dalton amorphin and alpha-actinin and their relation to structure

The conclusions arrived at as a result of this work can be summarized as follows: (a) We have found that there is an 85,000-dalton protein, which we have called 85K amorphin, associated with the Z-band of chicken pectoralis muscle myofibrils. We have isolated and purified this protein. It is not a structural component of the Z-filaments since it can be extracted completely without extraction of the Z-filaments. Extraction of 85K amorphin results in loss of specific staining of the Z-band with fluorescence specific anti-85K amorphin. (b) We have found that alpha-actinin is the structural component of the Z-filaments, since extraction of alpha-actinin is accompanied by loss of the Z-filament structure.