Protein, a New Fibrous Protein of Skeletal Muscle: Properties

¹ From the Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, and the Marine Biological Laboratory, Woods Hole, Massachusetts

Solutions of D protein contain a fibrous sub-fraction, protein, whose presence is demonstrated by measurements of sedimentation rate, viscosity and flow birefringence. The presence of such a component is further indicated by fibrous material in electronmicrographs. Dissociation of the protein molecule can be accomplished by lowering the ph. Reassociation occurs when the ph is raised. Possible relationships between protein and tropomyosin are discussed. It seems possible that protein may form the elastic filaments in the center of the sarcomere, recently described by several authors.