title: Brain adducin: a protein kinase C substrate that may mediate site-directed assembly at the spectrin-actin junction.
abstract: Erythrocyte adducin is a membrane skeletal protein that binds to calmodulin, is a major substrate for protein kinase C, and associates preferentially with spectrin-actin complexes. Erythrocyte adducin also promotes association of spectrin with actin, and this activity is inhibited by calmodulin. This study describes the isolation and characterization of a brain peripheral membrane protein closely related to erythrocyte adducin. Brain and erythrocyte adducin have at least 50% antigenic sites in common, each contains a protease-resistant core of Mr = 48,000-48,500, and both proteins are comprised of two partially homologous polypeptides of Mr = 103,000 and 97,000 (erythrocytes) and Mr = 104,000 and 107,000-110,000 (brain). Brain and erythrocyte adducin associate preferentially with spectrin-actin complexes as compared to spectrin or actin alone, and both proteins also promote binding of spectrin to actin. Brain adducin binds calmodulin in a calcium-dependent manner, although the Kd of 1.3 microM is weaker by 5-6-fold than the Kd of erythrocyte adducin for calmodulin. Brain adducin is a substrate for protein kinase C in vitro and can accept up to 2 mol of phosphate/mol of protein. Adducin provides a potential mechanism in cells for mediating site-directed assembly of additional spectrin molecules and possibly other proteins at the spectrin-actin junction. Brain tissue contains 12 pmol of adducin/mg of membrane protein, which is the most of any tissue examined other than erythrocytes, which have 50 pmol/mg. The presence of high amounts of adducin in brain suggests some role for this protein in specialized activities of nerve cells.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001798:Blood Proteins; D001923:Brain Chemistry; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000032:analysis; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000276:immunology; D004912:Erythrocytes / Q000032:analysis; D007118:Immunoassay; D046911:Macromolecular Substances; D008970:Molecular Weight; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D013049:Spectrin / Q000378:metabolism*; D000099291:Adducins
chemical_list: D000199:Actins; D001798:Blood Proteins; D002118:Calcium; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D000939:Epitopes; D046911:Macromolecular Substances; D010710:Phosphates; D011493:Protein Kinase C; D013049:Spectrin; D000099291:Adducins