Lymphocyte calmodulin and its participation in the stimulation of T lymphocytes by mitogenic lectins.

H Nakabayashi, H Komada, T Yoshida, H Takanari, K Izutsu

Department of Pathology, Mie University School of Medicine, Japan.

Biology of the cell / under the auspices of the European Cell Biology Organization 1992

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Calmodulin was purified from human tonsillar lymphocytes utilizing calcium-dependent binding of calmodulin to fluphenazine-Sepharose. The molecular weight and phosphodiesterase activation of the lymphocyte calmodulin were very similar to those of purified bovine brain calmodulin. Trifluoperazine (TFP), a calmodulin inhibitor, suppressed lymphocyte stimulation as assessed by 3H-thymidine incorporation into DNA of lectin-stimulated lymphocytes. TFP had no effect on the early 45Ca2+ uptake induced by mitogenic lectins, although this latter was inhibited by verapamil which also suppressed the 3H-thymidine incorporation. The results are in keeping with the interpretation that the inhibition of T cell stimulation by TFP was not due to suppression of Ca2+ uptake, but due to inactivation of Ca(2+)-calmodulin complex which might be formed subsequent to Ca2+ entry into the cell.

Citation

H Nakabayashi, H Komada, T Yoshida, H Takanari, K Izutsu. Lymphocyte calmodulin and its participation in the stimulation of T lymphocytes by mitogenic lectins. Biology of the cell / under the auspices of the European Cell Biology Organization. 1992;75(1):55-9