CA2+/calmodulin binds to and modulates P/Q-type calcium channels

Article Abstract:

Calcium entering through P/Q-type channels promotes Ca2+/calmodulin binding to the alpha-1A subunit, according to research designed to identify proteins that influence P/Q-type calcium-channel function through direct protein-protein interactions. The connection between Ca2+/calmodulin and the channel speeds up inactivation, boosts recovery from inactivation and increases calcium influx by making the calcium current greater after full recovery from inactivation. Association of calmodulin with small conductance calcium-activated potassium channels is vital for their gating by calcium.

Research, Calmodulin, Calcium-binding proteins, Calcium binding proteins

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Modulation of Ca2+ channels by G-protein beta-gamma subunits

Article Abstract:

G-protein beta-gamma subunits modulate Ca2+ channels. The alpha(sub 1A), beta(sub 1b) and alpha2-delta subunits of P/Q type Ca2+ channels were cotransfected in tsA-201 cells to analyze the voltage dependence of the stimulation of Ba2+ currents induced by voltage step protocols. Transfection of G protein beta-gamma subunits into cells, expressing calcium channels induces modulation similar to that caused by the activation of G protein coupled receptors. G-protein alpha subunits have no influence on the modulation of Ca2+ channels.

G proteins, Biological response modifiers

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Voltage-dependent potentiation of L-type Ca2+ channels due to phosphorylation by cAMP-dependent protein kinase

Article Abstract:

Tetanic trains of action potentials appear to potentiate Ca2+ channel activity, leading to increased contractile force. A shift in the voltage dependence of channel activation to more negative membrane potentials and phosphorylation by cyclic AMP-dependent protein kinase make this possible. A single conditioning prepulse of 0 to +89 mV for 200 ms made L-type Ca2+ currents potentiate strongly for activation at -29 mV.

Muscle contraction, Protein kinases

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