Journal
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
Volume 444, Issue 1-2, Pages 202-212Publisher
SPRINGER-VERLAG
DOI: 10.1007/s00424-002-0791-3
Keywords
lipid bilayers; phosphorylation; protein kinase; ryanodine receptor; sarcoplasmic reticulum
Categories
Funding
- NHLBI NIH HHS [R01-HL57832] Funding Source: Medline
Ask authors/readers for more resources
The effects of protein-kinase- (PKA-) dependent phosphorylation on the stationary gating kinetics of single ryanodine receptor (RyR) channels was defined. The single-channel activity from canine cardiac RyR was reconstituted into planar lipid bilayers. Exogenously applied PKA increased the single-channel open probability (P-o) of both native and purified cardiac RyR channels, after preincubation with ATP and Mg2+. The action of PKA on the RyR channel occurred only in the presence of ATP and adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS), but not in the presence of 5'-adenylimidodiphosphate (AMP-PCP). Thus, the action of PKA requires the presence of a hydrolyzable ATP analog. PKA-induced channel activation was blocked by specific PKA inhibitors. All these results confirmed that the RyR channel can be phosphorylated by exogenous protein kinase. The gating kinetics of single RyR channels before PKA treatment were significantly altered by ATP and Mg2+ as physiological ligands. In contrast, after PKA treatment, neither ATP nor Mg2+ significantly alters the gating kinetics of these channels. PKA-dependent phosphorylation thus decreases the ATP and Mg2+ apparent sensitivity in most of the gating parameters of single RyR channels. The phosphorylated RyR channels open and close more frequently, stay open for longer, and stay closed for shorter periods. The dwell-time histograms obtained demonstrate that the phosphorylated and the dephosphorylated channels have strikingly different open and closed kinetics at physiological cytoplasmic concentrations of Mg and ATP.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available