Mg. Yefimova et al., TRANSFERRIN AND FERRITIN MODULATE THE ACTIVITY OF BRAIN CALCIUM-CALMODULIN-DEPENDENT PHOSPHODIESTERASE, Biochemistry, 62(2), 1997, pp. 165-170
The effect of the key iron homeostasis proteins transferrin and ferrit
in on the activity of partially purified brain calcium-calmodulin-depe
ndent phosphodiesterase (CaM-PDE, EC 3.4.1.17) were studied. Transferr
in and ferritin were found to be potent natural activators of CaM-PDE.
The key factor determining the degree of activation by these proteins
is their saturation with iron: apotransferrin activated CaM-PDE 6-7-f
old; iron-poor brain ferritin and liver apoferritin (taken for compari
son) activated the enzyme 4-5- and 2-fold, respectively. Diferric tran
sferrin and iron-rich liver ferritin had no effects on the enzyme acti
vity. Transferrin and ferritin (both in apo- and iron-saturated forms)
did not change the activity of calmodulin-phosphodiesterase complex.
The data suggest that apotransferrin and iron-poor transferrin are inv
olved in the regulation of cyclic nucleotide content in nervous tissue
.