E-Conference: Defining Calcium Entry Signals
Calcium entry mechanisms
11 June 2004
Like Ken Byron, Trevor has raised an important question concerning the operation of other entery signals. The hypothesis I proposed certainly does not preclude other entry mechanisms especially with regard to their integration into the larger issue of how they contribute to the generation of Ca2+ spikes. The key point is that any entry mechanism must operate in a dose dependent manner over the physiological range that induced normal Ca2+ spiking. In my hypothesis, I tried to explain how the conformational coupling mechanism functions to feed Ca2+ into the ER to sensitize the uncoupled IP3Rs for a subsequent Ca2+ spike. This hypothesis certainly does not preclude other mechanisms as long as they can operate at these low agonist concentrations where entry plays a priming role. This is a somewhat different role for Ca2+ entry than Trevor has proposed recently where he placed most emphasis on entry contributing directly to the spike.
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