Mutations at two distinct sites within the channel domain M2 alter calcium permeability of neuronal alpha 7 nicotinic receptor.

摘要: Abstract The relative permeability for sodium, potassium, and calcium of chicken alpha 7 neuronal nicotinic receptor was investigated by mutagenesis the channel domain M2. Mutations in "intermediate ring" negatively charged residues, located at cytoplasmic end M2 (site 1), reduce without significantly modifying other functional properties (activation desensitization) receptor; a similar change ion selectivity is also noticed when mutations site 1 are done context mutant that conducts ions desensitized state. Moreover, two adjacent rings leucines synaptic 2) have multiple effects. They abolish permeability, increase apparent affinity acetylcholine 10- to 100-fold, augment Hill numbers (up 4.6-5.0) dose-response relationships, slow rates ionic response onset, lower extent desensitization. these topographically distinct sites within selectively alter transport affecting permeabilities sodium potassium.