title: Expression of the beta subunit of spectrin in nonerythroid cells.
abstract: Antibodies raised against electrophoretically purified chicken erythrocyte beta subunit of spectrin, called "beta-spectrin," have been used to demonstrate the presence of an immunoreactive form of this polypeptide in nonerythroid tissues. Immunoautoradiography shows that, in chicken erythrocytes, this antiserum reacts with beta-spectrin (Mr 220,000) and another polypeptide (Mr 230,000) that, by two-dimensional tryptic peptide analysis, shows extensive homology with beta-spectrin but not with the alpha subunit of spectrin, called "alpha-spectrin." Immunoautoradiography and immunoprecipitation of various chicken tissues with this antiserum shows that either one variant or both variants of beta-spectrin are expressed. Indirect immunofluorescence reveals that the antiserum reacts with a plasma membrane-associated component of erythroid and some nonerythroid cells. Particularly strong fluorescence is observed in skeletal and cardiac muscle cells where beta-spectrin appears to form a grid-like network along the inner surface of the sarcolemma. The noncoordinated distribution of alpha- and beta-spectrin variants indicates that their expression may be tailored to the functional requirements of the plasma membrane in different cells.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002462:Cell Membrane / Q000032:analysis*; D002645:Chickens; D004910:Erythrocyte Membrane / Q000032:analysis; D005455:Fluorescent Antibody Technique; D014644:Genetic Variation; D007106:Immune Sera; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000235:genetics*; D008970:Molecular Weight; D009132:Muscles / Q000032:analysis; D009928:Organ Specificity; D010446:Peptide Fragments / Q000032:analysis; D013049:Spectrin / Q000235:genetics*; D014357:Trypsin
chemical_list: D007106:Immune Sera; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010446:Peptide Fragments; D013049:Spectrin; D014357:Trypsin