Abstract
Glycine receptors (GlyRs) provide the main inhibitory neurotransmission in spinal cord and brain-stem synapses of vertebrates. Fucile et al. (2000) discovered that elevation of intracellular Ca2+ caused rapid potentiation of GlyRs. This modulation develops in less than 100 ms. It is characterized by an increase in GlyR apparent affinity for glycine. It has been suggested that the phenomenon of Ca-induced potentiation involves an unknown Ca2+-binding protein (CaBP). Using the yeast two-hybrid system, screening of a human brain cDNA library against the cytoplasmic loop of human alpha 1 subunit (GlyRh1) allowed us to identify five new interactors. One of them belongs to the family of Ca-binding proteins. We analyzed the effect of “short” forms of this protein (CaBP-1) on functional properties of GlyRh1 expressed in HEK-293 and CHO cells. Using whole-cell recordings and rapid agonist application, we constructed concentration dependences of glycine-induced currents. This analysis revealed statistically significant differences in EC50s between control cells (expressing only GlyRh1) and those expressing CaBP-1. In HEK-293 cells recorded under conditions of low intracellular Ca concentration (BAPTA 20 mM in the recording pipette), EC50 for glycine in control cells and expressing GlyRh1+CaBP-1 were, correspondingly, 68 ± 49 μM (n = 29) and 409 ± 421 μM (n = 60). In CHO cells, EC50 were 54 ± 43 μM (n = 25) and 123 ± 104 μM (n = 28). The differences were not statistically significant for recordings made with an intracellular solution containing high Ca concentration (50 μM). Under these conditions, EC50 values were correspondingly 35 ± 28 μM (n = 7) and 64 ± 38 μM (n = 7). These results suggest that CaBP-1 causes a decrease of GlyR sensitivity to agonist interacting with the cytoplasmic domain of GlyR.
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Original Russian Text © S. Buldakova, E. Real, Y. Jacob, P. Bregestovski, 2007, published in Tsitologiya, Vol. 49, No. 1, 2007, pp. 79–82.
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Buldakova, S., Real, E., Jacob, Y. et al. Calcium-dependent modulation of human glycine receptors expressed in cultivated cell lines. Cell Tiss. Biol. 1, 30–33 (2007). https://doi.org/10.1134/S1990519X0701004X
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DOI: https://doi.org/10.1134/S1990519X0701004X