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Neurotransmitter release from synaptic vesicles is triggered by voltage-gated calcium influx through P/Q-type or N-type calcium channels. Purification of N-type channels from rat brain synaptosomes initially suggested molecular interactions between calcium channels and two key proteins implicated in exocytosis: synaptotagmin I and syntaxin 1.(More)
Nerve terminal protein complexes implicated in exocytosis were examined by immuno-isolation from rat brain synaptosomes. Immunoprecipitation with anti-syntaxin or anti-VAMP antibodies revealed a syntaxin-SNAP25-VAMP-synaptotagmin complex. Anti-VAMP antibodies also trapped a distinct VAMP-synaptophysin complex. A similar fraction (about 70%) of N-type(More)
A toxin was purified to homogeneity from the venom of the South American armed spider Phoneutria nigriventer and found to have a molecular mass of 8600 Da and a C-terminally amidated glycine residue. It appears to be identical to Toxin 1 (Tx1) isolated previously from this venom. Tx1 reversibly inhibited sodium currents in Chinese hamster ovary cells(More)
Recent studies suggested that autoantibodies that bind to voltage-dependent calcium channels and activate calcium entry may play a role in the progressive degeneration of motoneurons in sporadic amyotrophic lateral sclerosis. Immunoassays were performed to assess autoantibody titer in patients with amyotrophic lateral sclerosis or Lambert-Eaton myasthenic(More)
Solubilized 125I-omega conotoxin MVIIC receptors from rat cerebellum were immunoprecipitated by antibodies directed against the calcium channel alpha 1A subunit. Anti-alpha 1A antibodies recognized a 240-220, 180 and 160 kDa proteins in immunoblots of cerebellar membranes. Disuccinimidyl suberate cross-linked 125I-omega conotoxin MVIIC to an alpha 2(More)
P- and Q-type calcium channels, which trigger rapid neurotransmitter release at many mammalian synapses, are blocked by omega-conotoxin MVIIC. 125I-omega-Conotoxin MVIIC binding to rat cerebellar synaptosomes was not displaced by omega-conotoxins GVIA or MVIIA (Ki > 1 microM), which are selective for N-type calcium channels. Solubilized 125I-omega-conotoxin(More)
omega-Conotoxin-sensitive N-type calcium channels control neurotransmitter release at the nerve terminal and interact with proteins implicated in secretion. Solubilized omega-conotoxin receptors from rat brain synaptic membrane were immunoprecipitated by antibodies against calcium channel alpha 1 subunits, syntaxin, and a 105-kDa plasma membrane protein. A(More)
The binding of omega-conotoxin to isolated rat neurohypophysial nerve terminals, its effect on the depolarization-induced increase of cytoplasmic Ca2+ and on the potassium and electrically-induced release of vasopressin (AVP) have been studied. The results show that isolated neurosecretory nerve endings have calcium channels with a high affinity for(More)
Immunoglobulin G fractions from patients with Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disease of neuromuscular transmission, immunoprecipitate 125I-labeled omega-conotoxin GVIA-labeled calcium channels solubilized from rat brain. A 58-kDa antigen was detected by probing Western blots of partially purified calcium channels with LEMS plasma(More)
Plasma from patients with Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disease of neuromuscular transmission, contains antibodies that immunoprecipitate 125I-omega-conotoxin GVIA labeled-calcium channels solubilized from rat brain. These antibodies label a 58-kDa protein in Western blots of partially purified 125I-omega-conotoxin receptor(More)