The nature of the extra protein fraction from myofibrils of striated muscle

Abstract

The extra protein fraction of skeletal muscle myofibrils consists of a complex mixture of proteins which can be resolved into 4 main fractions by chromatography on diethylaminoethylcellulose. About 30% of the extra protein consisted of a complex fraction containing aldolase activity and resembling the sarcoplasmic proteins in chromatographic behavior. Tropomyosin was a somewhat variable component of the extra protein representing 4-22% of the total protein N. About 20% of the extra protein consisted of a protein insoluble in water which may be a component of the Y-protein of Dubuisson (1950). A ribonucleoprotein function of myofibrillar origin was isolated from the extra protein.