Binding of Lambert-Eaton myasthenic syndrome IgG to synaptosomal proteins does not correlate with an inhibition of calcium uptake.
The immunochemical and functional properties of IgG fractions from patients with Lambert-Eaton myasthenic syndrome (LEMS) were examined in chick and rat synaptosomes. LEMS IgG immunoprecipitated 125I-omega conotoxin GVIA (125I-omega CgTx) labeled N-type calcium channels solubilized from both tissues, and reacted with a 65 kDa protein band in immunoblots of rat synaptosomes. Depolarization-induced 45Ca2+ influx into chick synaptosomes was partially inhibited by omega CgTx, whereas influx into rat synaptosomes was insensitive to omega CgTx. No effect of LEMS sera or IgG on 45Ca2+ uptake was apparent in either preparation.
Martin-Moutot
N
N
Neurobiologie des canaux ioniques, INSERM U 374, Institut Jean Roche, Faculté de Médecine Nord, Marseille, France.
Lang
B
B
Newsom-Davis
J
J
Seagar
M
M
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism; D002645:Chickens; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D015624:Lambert-Eaton Myasthenic Syndrome / Q000097:blood*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D011233:Precipitin Tests; D051381:Rats; D013574:Synaptosomes / Q000378:metabolism*; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D007074:Immunoglobulin G; D009419:Nerve Tissue Proteins; D010455:Peptides; D020866:omega-Conotoxin GVIA; D002118:Calcium