Rapid ligand-regulated gating kinetics of single inositol 1,4,5-trisphosphate receptor Ca2+ release channels.
The ubiquitous inositol 1,4,5-trisphosphate receptor (InsP(3)R) intracellular Ca(2+) release channel is engaged by thousands of plasma membrane receptors to generate Ca(2+) signals in all cells. Understanding how complex Ca(2+) signals are generated has been hindered by a lack of information on the kinetic responses of the channel to its primary ligands, InsP(3) and Ca(2+), which activate and inhibit channel gating. Here, we describe the kinetic responses of single InsP(3)R channels in native endoplasmic reticulum membrane to rapid ligand concentration changes with millisecond resolution, using a new patch-clamp configuration. The kinetics of channel activation and deactivation showed novel Ca(2+) regulation and unexpected ligand cooperativity. The kinetics of Ca(2+)-mediated channel inhibition showed the single-channel bases for fundamental Ca(2+) release events and Ca(2+) release refractory periods. These results provide new insights into the channel regulatory mechanisms that contribute to complex spatial and temporal features of intracellular Ca(2+) signals.
Mak
Don-On Daniel
DO
Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. dmak@mail.med.upenn.edu
Pearson
John E
JE
Loong
King Pan Campion
KP
Datta
Suman
S
Fernández-Mongil
Marisabel
M
Foskett
J Kevin
JK
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002460:Cell Line; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism*; D007313:Insecta; D015640:Ion Channel Gating / Q000502:physiology*; D008024:Ligands; D018408:Patch-Clamp Techniques
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008024:Ligands; D002118:Calcium