The amino terminal half of the nicotinic beta-subunit extracellular domain regulates the kinetics of inhibition by neuronal bungarotoxin.
Subtypes of nicotinic receptors previously reported to be unaffected by neuronal bungarotoxin (NBT), including alpha 3 beta 4-containing and muscle type (alpha 1 beta 1 gamma delta) receptors, are shown to be inhibited by this toxin, but with rapid kinetics of onset and recovery. This inhibition is in contrast to the slow and prolonged inhibition of alpha 3 beta 2-containing receptors, suggesting that the beta subunits determine the kinetics of NBT inhibition of alpha 3 receptors. We have coexpressed chimeric beta subunits with alpha 3, and our results show that the first 121 amino acids of the beta subunit extracellular domain are sufficient to regulate the kinetics of NBT inhibition. This domain is also an important determinant of whether cytisine will act as a full agonist or a partial agonist of nicotinic receptors formed with alpha 3.
Molecular Neurobiology Laboratory, Salk Institute, San Diego, California 92186-5800.
R L
RL
Papke
R M
RM
Duvoisin
S F
SF
Heinemann
D000109:Acetylcholine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002038:Bungarotoxins / Q000494:pharmacology*; D003001:Cloning, Molecular; D005260:Female; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009474:Neurons / Q000502:physiology*; D018733:Nicotinic Antagonists; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000096:biosynthesis / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism
D002038:Bungarotoxins; D046911:Macromolecular Substances; D018733:Nicotinic Antagonists; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D011978:Receptors, Nicotinic; D011993:Recombinant Fusion Proteins; D000109:Acetylcholine