Related Experiment Video
Updated: Sep 26, 2026

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
Published on: October 1, 2010
A mutation in transmembrane domain II of the 5-hydroxytryptamine(3A) receptor stabilizes channel opening and alters
J S Sessoms-Sikes1, Margaret E Hamilton, Li-Xin Liu
1Department of Pharmacology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
Abstract:
Mutant 5-hydroxytryptamine (5-HT)3A receptors, in which changes were made at Ile294, position 16', of the second transmembrane domain, were assessed for alterations in macroscopic response kinetics and modulation by alcohols. Function of heterologously expressed receptors was measured in Xenopus oocytes in the two-electrode voltage clamp configuration and in human embryonic kidney 293 cells using whole cell patch-clamp electrophysiological recordings with rapid drug application. Compared with the wild-type receptor, a decrease in the 5-HT EC50 value in the Ile294Thr mutant was observed, whereas an increase in the 5-HT EC50 value in the Ile294Leu mutant was measured. Ile294Thr receptors showed a marked reduction in the extent of desensitization. Ethanol and 2,2,2-trichloroethanol (TCEt) enhanced 5-HT-mediated currents in wild-type and Ile294Leu receptors, but inhibited or had little stimulatory effect in the Ile294Thr mutant. Kinetic analysis revealed that in the presence of TCEt, the slope of activation was unchanged in the Ile294Thr mutant and increased in the wild-type receptor. Alcohol cutoff was altered with wild-type = heptanol and Ile294Leu = hexanol. Kinetic changes in the Ile294Thr mutant that favor the open channel state, as well as reduction in the rate of channel activation in the presence of TCEt, likely underlie this mutant's altered response to n-chain alcohols.
More Related Videos
07:30HSV-Mediated Transgene Expression of Chimeric Constructs to Study Behavioral Function of GPCR Heteromers in Mice
Published on: July 9, 2016
08:04Identification and Classification of Position-specific GABAA Receptor Subunit Missense Variants for Their Role In Hippocampal Pyramidal Neurons
Published on: June 6, 2025
Related Concept Videos
Ligand-Gated Ion Channel Receptor: Gating Mechanism
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Ligand-gated Ion Channels
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
The Two-State Receptor Model
The binding affinity of a drug determines its interaction with one...
Neurochemical Transmission: Sites of Drug Action
Cooperative Allosteric Transitions