Mutation of serine 1928 of the alpha 1C subunit to alanine abolishes the modulation of the expressed cardiac Ca2+ channel by PKA inhibitors.
Phosphorylation of serine 1928 of the alpha 1C subunit is identified as a potential key mediator of PKA modulation on the cardiac voltage-dependent Ca2+ channel.
The well-characterized enhancement of the cardiac Ca2+ L-type current by protein kinase A (PKA) is not observed when the corresponding channel is expressed in Xenopus oocytes, possibly because it is fully phosphorylated in the basal state. However, the activity of the expressed channel is reduced by PKA inhibitors. Using this paradigm as an assay to search for PKA sites relevant to channel modulation, we have found that mutation of serine 1928 of the alpha 1C subunit to alanine abolishes the modulation of the expressed channel by PKA inhibitors. This effect was independent of the presence of the beta subunit. Phosphorylation of serine 1928 of alpha 1C may mediate the modulatory effect of PKA on the cardiac voltage-dependent ca2+ channel.
Perets et al. (Mon,) reported a other. Mutation of serine 1928 of the alpha 1C subunit to alanine vs. Wild-type channel was evaluated on Modulation of the expressed channel by PKA inhibitors. Mutation of serine 1928 of the alpha 1C subunit to alanine abolishes the modulation of the expressed cardiac Ca2+ channel by PKA inhibitors.
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