Definition and characterization of the short alphaA-conotoxins: a single residue determines dissociation kinetics from the fetal muscle nicotinic acetylcholine receptor.
We report the definition and characterization of a conotoxin subfamily, designated the short alphaA-conotoxins (alphaA(S)) and demonstrate that all of these share the unique property of selectively antagonizing the fetal subtype of the mammalian neuromuscular nicotinic acetylcholine receptor (nAChR). We have characterized newly identified alphaA(S)-conotoxins from Conus pergrandis and have conducted a more detailed characterization of alphaA-conotoxins previously reported from additional Conus species. Among the results, the characterization of the short alphaA-conotoxins revealed diverse kinetics of a block of the fetal muscle nAChR, particularly in dissociation rates. The structure-function relationships of native alphaA(S)-conotoxins and some analogues revealed a single amino acid locus (alternatively either His or Pro in native peptides) that is a critical determinant of the dissociation kinetics. The unprecedented binding selectivity for the fetal muscle nAChR, coupled with the kinetic diversity, should make alphaA(S)-conotoxins useful ligands for a diverse set of studies. The rapidly reversible peptides may be most suitable for electrophysiological studies, while the relatively irreversible peptides should be most useful for binding and localization studies.
Teichert
Russell W
RW
Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA. teichert@biology.utah.edu
López-Vera
Estuardo
E
Gulyas
Jozsef
J
Watkins
Maren
M
Rivier
Jean
J
Olivera
Baldomero M
BM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D020916:Conotoxins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D052078:Conus Snail / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000196:embryology / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000037:antagonists & inhibitors; D051381:Rats; D011978:Receptors, Nicotinic / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus / Q000378:metabolism
D020916:Conotoxins; D010456:Peptides, Cyclic; D011978:Receptors, Nicotinic; C492637:alphaA-conotoxin OIVA; C104576:alphaA-conotoxin PIVA