ABSTRACT
Three peptides of the ligand-gated channels of the central nervous system have been already sequenced, that is two subunits of the gamma-aminobutyric acid receptor channel, and one of the glycine receptor channel. The sodium channel belongs to the first fully characterized channels of the nervous system. Direct chemical identification of sodium channel components in situ was done by specific covalent labelling of a derivative of alpha scorpion toxin which revealed covalent binding with two polypeptides, designated the alpha and beta, subunits of the sodium channel. The physiological role of the calcium channels is based on the pivotal role of Ca2+ as an intracellular second messenger. Radiolabeled Dihydropyridine were used to study their binding affinity with various tissues. The experiments were performed on chick DGR cells, where types N and L of calcium channels have been found, but no T channels. It is generally accepted that information generated in the brain involves communication between neurons through release of neurotransmitters at synapses.
