Differential effect of PKA on the Ca2+ release kinetics of the type I and III InsP3 receptors.
The effects of protein kinase A (PKA) on the inositol 1,4,5-trisphosphate (InsP(3)) receptor isoforms type I and type III were studied. The effects of PKA on the extent and rate constants for InsP(3)-induced Ca(2+) release (IICR) were different for the two isoforms. The effects of PKA on the type I isoform showed a biphasic relationship dependent upon the concentration of PKA used. At low concentrations of PKA (<50U/ml), both the extent and rate constants for IICR increased, while at higher concentrations (>200U/ml) the extent and rate constants decreased. The type III isoform showed only an increase in the extent of IICR and not in the rate constants. The effects of PKA on the type I InsP(3) receptor using single channel electrophysiological studies were also investigated. The stimulatory effect of PKA is due to an increase in conductance levels and not to a change in the mean open time of the channel.
Dyer
Jeanette L
JL
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Mobasheri
Hamid
H
Lea
Edward J A
EJ
Dawson
Alan P
AP
Michelangeli
Francesco
F
D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D015640:Ion Channel Gating; D010766:Phosphorylation; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium