title: Beta 2 subunits of sodium channels from vertebrate brain. Studies with subunit-specific antibodies.
abstract: The sodium channel purified from rat brain is composed of three subunits: alpha (Mr 260,000), beta 1 (Mr 36,000), and beta 2 (Mr 33,000). alpha and beta 2 subunits are linked through disulfide bonds. Procedures are described for preparative isolation of the beta 1 and beta 2 subunits under native conditions. Pure beta 2 subunits obtained by this procedure were used to prepare a specific anti-beta 2 subunit antiserum. Antibodies purified from this serum by antigen affinity chromatography recognize only disulfide-linked alpha beta 2 complexes and beta 2 subunits in immunoblots, and immunoprecipitate 32P-labeled alpha subunits of purified sodium channels having intact disulfide bonds, but not those of sodium channels from which beta 2 subunits have been detached by reduction of disulfide bonds. These antibodies also immunoprecipitate 89% of the high affinity saxitoxin-binding sites from rat brain membranes, indicating that nearly all sodium channels in rat brain have disulfide-linked alpha beta 2 subunits. Approximately 22% of beta 2 subunits in adult rat brain are not disulfide-linked to alpha subunits. Anti-beta 2 subunit antibodies are specific for sodium channels in the central nervous system and will not cross-react with sodium channels in skeletal muscle or sciatic nerve. The brains of a broad range of vertebrate species, including electric eel, are shown to express sodium channels with disulfide-linked alpha beta 2 subunits.
mesh_terms: D029845:Amphibian Proteins; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry; D002352:Carrier Proteins / Q000276:immunology; D003429:Cross Reactions; D004220:Disulfides; D007473:Ion Channels / Q000032:analysis* / Q000276:immunology; D008970:Molecular Weight; D009132:Muscles / Q000032:analysis; D010525:Peripheral Nerves / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*
chemical_list: D029845:Amphibian Proteins; D000906:Antibodies; D002352:Carrier Proteins; D004220:Disulfides; D007473:Ion Channels; C027525:saxitoxin-binding protein, Rana catesbeiana; D012964:Sodium