జర్నల్ ఆఫ్ బయోక్వివలెన్స్ & బయోఎవైలబిలిటీ

నైరూప్య

Na⁺/K⁺ Pump α₃ Isoform is a Universal Membrane Sensor for Weak Environmental Signals

Sinerik Ayrapetyan

In present review are presented data on functional role of α3-Na+/K+ pump isoform-dependent Ca exchange
in weak signal transduction in cells. According to the classic “Membrane theory” signals can modulate membrane functional activity by changing its conductive function: activation or inactivation of ionic channels leading to cell membrane depolarization or hyper-polarization. However, at present it is well established that there are a number of non-conductive mechanisms in membrane through which extra-weak signals having intensity even far from the threshold of channel activation could modulate the cell membrane function. The previous study on the sensitivity of α3 receptors having higher ouabain affinity to different weak physical and chemical signals showed that they are universal sensors also for different environmental factors. Such sensitivity is determined by α3- Na+/K+ pump isoform-dependent Na+/Ca2+ exchange system, having crucial role in controlling cell hydration and intracellular Ca homeostasis. It is known that the latter regulates the number of functionally active protein molecules (enzymes, chemoreceptors and ionic channels) in membrane by its surface changing and the activity of intracellular macromolecules by protein- folding mechanism. On the basis of these data it is suggested that these carrier driven transporting mechanisms can be considered as candidates for extra-sensitive and universal sensors in neuromembrane through which the biological effects of extra-weak signals are realized.The overall aim of this chapter is to present a brief review on the physiological role of α3 isoform Na+/K+ pump-dependent Na+/Ca2+ exchange as a universal and extra-sensitive pathway through which the biological effects of weak signals on cells are realized.