Related Experiment Video
Updated: Feb 3, 2026

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
Published on: October 1, 2010
Comparative electrophysiological analysis of the bile acid-sensitive ion channel (BASIC) from different species
Pia Lenzig1, Monika Wirtz1, Dominik Wiemuth2
1Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.
Abstract:
Despite the identification of cholangiocytes in the liver and unipolar brush cells in the cerebellum as sites of expression, the physiological function of the bile acid-sensitive ion channel (BASIC) remains unknown. Rat BASIC (rBASIC) and mouse BASIC (mBASIC) share 97% of their amino acid sequence but show strikingly different biophysical properties. rBASIC is inactive at rest while mBASIC is constitutively active, when expressed in Xenopus oocytes. This conundrum rendered the identification of the physiological function even more difficult. In this study, we investigated the electrophysiological and pharmacological properties of BASIC from rat, mouse, and human in Hek293 cells using the patch clamp technique. Surprisingly, in Hek293 cells, rBASIC and mBASIC showed almost completely identical properties. Both are blocked by extracellular Ca2+ and thus are inactive at rest; both are selective for Na+, show similar affinities for extracellular Ca2+, were inhibited by diminazene, and activated by various bile acids. This is in contrast to previous results derived from Xenopus oocytes as expression system and suggests that the cell type is important for shaping the biophysical properties of BASIC. Furthermore, we compared hBASIC with rBASIC and mBASIC and observed similar properties between these channels with one exception: the bile acid sensitivity profile of hBASIC is different from rBASIC and mBASIC; hBASIC is more sensitive to bile acids which are abundant in human bile but not in rodent bile. Taken together, these results suggest similar physiological roles for BASIC in different species.
More Related Videos
Related Concept Videos
Ion Channels
Ion channels are specialized integral membrane proteins on the plasma membrane that allow...
Ions as Acids and Bases
Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt’s constituent ions. For example, dissolving the ammonium chloride in water results in its dissociation, as described by the equation:
Non-gated Ion Channels
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism....
Mechanically-gated Ion Channels
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...
G-Protein Gated Ion Channels
Sensory...

