Influence of Ca²⁺ Oscillatory Influx on Membrane Ca²⁺-ATPase Activity: a Kinetic Model

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B. N. Goldstein^*, A. A. Mayevsky, and D. T. Zakrjevskaya

Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; fax: (7-0967) 79-0553; E-mail: goldstein@iteb.ru

^* To whom correspondence should be addressed.

Received April 6, 2004; Revision received May 11, 2004

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A kinetic model for the membrane Ca²⁺-ATPase is considered. The catalytic cycle in the model is extended by enzyme auto-inhibition and by oscillatory calcium influx. It is shown that the conductive enzyme activity can be registered as damped or sustained Ca²⁺ pulses similar to observed experimentally. It is shown that frequency variations in Ca²⁺ oscillatory influx induce changes of pulsating enzyme activity. Encoding is observed for the signal frequency into a number of fixed levels of sustained pulses in the enzyme activity. At certain calcium signal frequencies, the calculated Ca²⁺-ATPase conductivity demonstrates chaotic multi-level pulses, similar to those observed experimentally.

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KEY WORDS: Ca²⁺-ATPase, oscillations, signal coding, kinetic model

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