title: Relationships of the spectrin complex of human erythrocyte membranes to the actomyosins of muscle cells.
abstract: Important similarities are reported between human smooth muscle actomyosin and the human erythrocyte spectrin complex, primarily components 1, 2, and 5 (Fairbanks G., Steck, T.L., and Wallach, D.F.H. (1971), Biochemistry 10, 2606). The actin-like protein, component 5, is identical with human uterine actin in its ability to form 50-70-A filaments to stimulate myosin ATPase activity, and to bind rabbit heavy meromyoson specit heavy meromyosin specifically. Antibodies to human smooth muscle myosin(uterine) were prepared which were monospecific. A weak but specific cross-reaction of these antisera with components 1 and/or 2 (spectrin) was characterized and at least 25% of the antimyosin antibodies showed a low affinity reaction iwth spectrin. Antibodies generated against a soluble complex of spectrin components 1 and 2 reacted only with component 1 and did not cross-react with myosin. In addition to these structural similarities between smooth muscle actomyosin and the spectrin complex, we have found that spectrin is involved in ATP-dependent erythrocyte shape changes (Sheetz, M.P., Painter, R.G., AND Singer, S.J. (1976B), Cold Spring Harbor Symp. Cell Motility (in press) and, therefore, the spectrin complex is also a mechanochemical protein system.
mesh_terms: D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D003168:Complement Fixation Tests; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D005779:Immunodiffusion; D007700:Kinetics; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009130:Muscle, Smooth / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D013049:Spectrin / Q000302:isolation & purification / Q000378:metabolism; D014599:Uterus / Q000378:metabolism
chemical_list: D000199:Actins; D001798:Blood Proteins; D046911:Macromolecular Substances; D013049:Spectrin; D000205:Actomyosin; D000251:Adenosine Triphosphatases; D009218:Myosins