A Shab potassium channel contributes to action potential broadening in peptidergic neurons.
We have cloned the gene for a potassium channel, Aplysia Shab, that is expressed in the bag cell neurons of Aplysia. The voltage dependence and kinetics of the Aplysia Shab current in oocytes match those of IK2, one of the two delayed rectifiers in these neurons. Like IK2, but in contrast with other members of the Shab subfamily, the Aplysia Shab current inactivates within several hundred milliseconds. This inactivation occurs by a process whose properties do not match those previously described for C-type and N-type mechanisms. Neither truncation of the N-terminus nor block by tetraethylammonium alters the time course of inactivation. By incorporating the characteristics of Aplysia Shab into a computational model, we have shown how this current contributes to the normal enhancement of action potentials that occurs in the bag cell neurons at the onset of neuropeptide secretion.
Quattrocki
E A
EA
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
Marshall
J
J
Kaczmarek
L K
LK
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D005260:Female; D007447:Invertebrate Hormones / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D008433:Mathematics; D008962:Models, Theoretical; D008969:Molecular Sequence Data; D009474:Neurons / Q000502:physiology*; D009865:Oocytes / Q000502:physiology; D016133:Polymerase Chain Reaction; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051669:Shab Potassium Channels; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014158:Transcription, Genetic; D014982:Xenopus laevis
D018076:DNA, Complementary; D007447:Invertebrate Hormones; D015221:Potassium Channels; D051669:Shab Potassium Channels; C085558:Shab protein, Aplysia; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D011188:Potassium