Related Experiment Video

Updated: Aug 23, 2026

Electromechanical Assessment of Optogenetically Modulated Cardiomyocyte Activity
12:52

Electromechanical Assessment of Optogenetically Modulated Cardiomyocyte Activity

Published on: March 5, 2020

MiRP1 modulates HCN2 channel expression and gating in cardiac myocytes

Jihong Qu1, Yelena Kryukova, Irina A Potapova

  • 1Department of Pharmacology, Columbia University, New York, NY 10032, USA.

The Journal of Biological Chemistry
|August 5, 2004
PubMed

Insights

MinK-related protein (MiRP1) enhances cardiac pacemaker channel (HCN2) function and assembly in heart cells. This interaction significantly increases current conductance and alters gating kinetics, revealing MiRP1

Area of Science:

  • Cardiovascular Physiology
  • Molecular Cardiology
  • Ion Channel Biophysics

Background:

  • MinK-related protein 1 (MiRP1) is known to interact with hyperpolarization-activated, cyclic nucleotide-gated (HCN) pacemaker channels.
  • Previous studies in heterologous systems showed inconsistent effects of MiRP1 on HCN channel function.
  • Both MiRP1 and HCN subunits are highly expressed in the sinoatrial node, crucial for cardiac impulse initiation.

Purpose of the Study:

  • To investigate the physiological effect of MiRP1 on HCN channel expression and function in cardiac cells.
  • To determine if MiRP1 acts as a regulatory subunit for HCN channels in a relevant cellular context.

Main Methods:

  • Adenovirus-mediated overexpression of hemagglutinin-tagged MiRP1 (HA-MiRP1) and HCN2 in neonatal rat ventricular myocytes.
  • Electrophysiological recordings to measure pacemaker currents and channel kinetics.
  • Co-immunoprecipitation assays to assess protein-protein interactions between MiRP1 and HCN2.

Main Results:

  • Co-expression of HA-MiRP1 with HCN2 increased maximal pacemaker current conductance by 4-fold compared to HCN2 alone.
  • HCN2 activation and deactivation kinetics became significantly faster at voltages between -60 and -95 mV with HA-MiRP1 co-expression.
  • Co-immunoprecipitation confirmed that both expressed and endogenous MiRP1 and HCN2 co-assemble within ventricular myocytes.

Conclusions:

  • MiRP1 functions as a beta subunit for HCN2 pacemaker channel subunits in cardiac cells.
  • MiRP1 significantly modulates HCN2 channel gating kinetics and current amplitude at physiologically relevant voltages.
  • This interaction has considerable physiological significance for cardiac impulse generation.

More Related Videos

Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique08:11

Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique

Published on: November 11, 2022

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice09:20

Microelectrode Array Recording of Sinoatrial Node Firing Rate to Identify Intrinsic Cardiac Pacemaking Defects in Mice

Published on: July 5, 2021

Related Concept Videos

G-Protein Gated Ion Channels01:21

G-Protein Gated Ion Channels

GPCRs are primarily responsible for our sense of smell, taste, and vision.  The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory organs,...
Cholinergic Receptors: Muscarinic01:25

Cholinergic Receptors: Muscarinic

The pharmacological actions of acetylcholine are elicited via its binding to two families of cholinergic receptors or cholinoceptors, namely, muscarinic and nicotinic receptors. Muscarinic receptors are G protein-coupled receptors and have five subtypes, M1–M5. All mAChR subtypes are activated by acetylcholine and blocked by the antagonist, atropine. 
The subtypes M1, M3, and M5 couple with the Gq subunit and activate the phospholipase C (PLC) activity, mobilizing intracellular Ca2+. Activation...
Mechanically-gated Ion Channels01:12

Mechanically-gated Ion Channels

Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous...
Ligand-Gated Ion Channel Receptor: Gating Mechanism01:30

Ligand-Gated Ion Channel Receptor: Gating Mechanism

Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...