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Physiological Ca2+ level and Ca2+-induced Permeability Transition Pore control protein phosphorylation in rat brain

T Azarashvili1, O Krestinina, I Odinokova

  • 1Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, RU-142290 Pushchino, Moscow region, Russia.

Cell Calcium
|July 31, 2003
PubMed

Insights

Calcium ions (Ca2+) regulate protein phosphorylation in rat brain mitochondria (RBM). This calcium signaling impacts low molecular mass phosphoproteins, influencing mitochondrial function and potentially opening the permeability transition pore (PTP).

Area of Science:

  • Mitochondrial biochemistry
  • Cellular signaling
  • Neuroscience

Background:

  • Rat brain mitochondria (RBM) exhibit protein phosphorylation at physiologically relevant ATP concentrations.
  • Calcium ions (Ca2+) are crucial intracellular messengers involved in various cellular processes.

Purpose of the Study:

  • To investigate the regulatory effects of Ca2+ on the phosphorylation of low molecular mass proteins in RBM.
  • To elucidate the role of Ca2+ concentration in modulating protein phosphorylation within physiological ranges.

Main Methods:

  • In vitro phosphorylation assays using [gamma-32P]ATP to measure protein phosphorylation.
  • Utilizing Ca2+ in physiological concentration ranges (10(-8) to 10(-6)M free Ca2+).
  • Employing inhibitors such as cyclosporin A (PTP inhibitor) and calmidazolium (calmodulin antagonist), and H-8 (protein kinase A inhibitor).

Main Results:

  • Ca2+ modulates phosphorylation of 3.5, 17, and 23kDa proteins in RBM.
  • Increased 32P incorporation into the 17kDa protein and decreased incorporation into the 3.5kDa protein were observed within the 10(-7) to 10(-6)M free Ca2+ range.
  • Ca2+-induced effects on phosphorylation were linked to Permeability Transition Pore (PTP) opening and modulated by calmodulin and protein kinase A.

Conclusions:

  • Physiological concentrations of Ca2+ act as a second messenger to control phosphorylation of low molecular mass phosphoproteins in RBM.
  • These Ca2+-dependent phosphorylation events are closely tied to Ca2+-induced PTP opening.
  • This study expands the known roles of Ca2+ in mitochondrial regulation beyond Krebs cycle dehydrogenases.

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