- 关于 Tocris
Ligand-gated ion channels are a large group of intrinsic transmembrane proteins that allow passage of ions upon activation by a specific chemical. Most endogenous ligands bind to a site distinct from the ion conduction pore and binding directly causes opening or closing of the channel. Ligands can bind extracellularly, e.g. glutamate, ACh and GABA, or intracellularly, e.g. Ca2+ on Ca2+-activated potassium channels. It is important to note that the ligand itself is not transported across the membrane. Ligand binding causes a drastic change in the permeability of the channel to a specific ion or ions; effectively no ions can pass through the channel when it is inactive but up to 107 ions per second can be allowed through upon ligand binding.
Multiple diseases arise from abnormal functioning of ligand-gated ion channels. For example, overactivation of NMDA glutamate receptors allows Ca2+ entry, leading to activation of the apoptotic pathway and neurotoxicity - a process that may play a part in many neurodegenerative disorders.