title: Similarities between the Mr 245,000 calmodulin-binding protein of the dogfish erythrocyte cytoskeleton and alpha-fodrin.
abstract: The Mr 245,000 calmodulin-binding protein of the dogfish erythrocyte cytoskeleton (D245) has been compared with human erythrocyte spectrin and mammalian brain fodrin [J. Levine and M. Willard (1981) J. Cell Biol. 90, 631-643]. Mammalian erythrocyte alpha-spectrin, brain alpha-fodrin, and D245 are all localized in the cell surface-associated cytoskeleton, and have similar molecular weights. Like mammalian erythrocyte spectrin, D245 was extracted from erythrocyte ghosts under low-ionic-strength conditions. However, D245 failed to bind an antibody which reacted strongly with both subunits of human erythrocyte spectrin. Unlike mammalian erythrocyte alpha- and beta-spectrin, D245 bound calmodulin in the absence of urea both in a "gel-binding" assay and in situ using azidocalmodulin [D.C. Bartelt, R.K. Carlin, G.A. Scheele, and W.D. Cohen (1982) J. Cell Biol. 95, 278-284]. Striking similarities were noted between D245 and alpha-fodrin in that both exhibited (a) comparable calcium-dependent calmodulin binding properties, (b) strong reactivity with two different anti-fodrin antibody preparations, (c) similar reactivity with antibody to brain CBP-I, now believed to be fodrin, (d) proteolytic degradation yielding an Mr 150,000 calmodulin-binding fragment, and (e) lack of reactivity with an anti-spectrin antibody. A protein with calmodulin-binding and anti-fodrin-binding properties similar to D245 was detected in cytoskeletal preparations of chicken erythrocytes. Moderate and consistent cross-reactivity of anti-fodrin with human erythrocyte alpha-spectrin was also observed. The data indicate that D245 is functionally and immunologically more closely related to alpha-fodrin than to alpha-spectrin of the mammalian erythrocyte.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins / Q000378:metabolism*; D002645:Chickens; D003599:Cytoskeleton / Q000378:metabolism*; D004284:Dogfish; D004285:Dogs; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D007120:Immunochemistry; D008840:Microfilament Proteins; D008970:Molecular Weight; D010749:Phosphoprotein Phosphatases / Q000097:blood*; D011485:Protein Binding; D013045:Species Specificity; D013049:Spectrin / Q000378:metabolism
chemical_list: D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D008840:Microfilament Proteins; D010749:Phosphoprotein Phosphatases; D013049:Spectrin