TO knowledge page — Physiome Model Repository

About

Landing page for the proteins constituting the transient outward potassium current (TO).

This channel transports potassium ions across the plasma membrane according to the concentration gradient. It is crucial in the early repolarisation of the cell membrane during the cardiac action potential, as it rapidly activates and inactivates following membrane depolarization

There are 2 variants for this current: fast I_{to, f} and slow I_{to, s}

TO channels are tetramers of pore-forming alpha subunits.

Subfamilies

The following list contains the known proteins which may form the TO current.

Variants within the human species
Name	Alias	Current	Gene	Structure	Interacts with
KCND2	Kv4.2	fast	Uniprot D2	PDB D2	KCND3/KChIP2/DPP6
KCND3	Kv4.3	fast	Uniprot D3	SMR D3	KCND2/KChIP2/DPP6
KCNA4	Kv1.4	slow	Uniprot A4	SMR A4
KCNA7	Kv1.7	slow	Uniprot A7	SMR A7

Literature

For further reading
Title	Author
The Molecular Physiology of the Cardiac Transient Outward Potassium Current (Ito) in Normal and Diseased Myocardium	Oudit et al.
Novel mechanism of transient outward potassium channel current regulation in the heart: implications for cardiac electrophysiology in health and disease	Bohnen et al.

Existing models

Link to other PMR workspaces or exposures
Title	Author
BG_TO	S Fong
A computational model of induced pluripotent stem-cell derived cardiomyocytes incorporating experimental variability from multiple data sources*^	Kernik et al.

Models denoted by [*] are not in bond graph form. Models denoted by [^] are part of a whole cell model.