Calmodulin and other protein substrates of casein kinase-2 (CK2) are not phosphorylated by CK2 holoenzyme under basal conditions. The non catalytic beta-subunit of CK2 is responsible for such a down-regulation which can be overcome by the addition of polylysine [Meggio, F. et al. (1992) Eur. J. Biochem. 205, 939-945]. Here we show that the peptide CVVKILKPVKKKKIKREIKILE, reproducing the basic insert 66-86 of CK2 catalytic subunit, can mimick polylysine in triggering the latent "calmodulin kinase" activity of CK2 holoenzyme, and that spermine and, to a lesser extent, spermidine, but not putrescine, can reversibly and dose-dependently counteract such an activation. Spermine also abolishes the stimulation by polybasic peptides of basal CK2 activity. These findings disclose the possibility that spermine may act in vivo as a negative regulator of CK2 activity toward a category of substrates, like calmodulin and ornithine decarboxylase, whose phosphorylation is dependent on polybasic peptides.

POLYAMINES AS NEGATIVE REGULATORS OF CASEIN KINASE-2 - THE PHOSPHORYLATION OF CALMODULIN TRIGGERED BY POLYLYSINE AND BY THE ALPHA[66-86] PEPTIDE IS PREVENTED BY SPERMINE

SARNO, STEFANIA;MARIN, ORIANO;MEGGIO, FLAVIO;PINNA, LORENZO
1993

Abstract

Calmodulin and other protein substrates of casein kinase-2 (CK2) are not phosphorylated by CK2 holoenzyme under basal conditions. The non catalytic beta-subunit of CK2 is responsible for such a down-regulation which can be overcome by the addition of polylysine [Meggio, F. et al. (1992) Eur. J. Biochem. 205, 939-945]. Here we show that the peptide CVVKILKPVKKKKIKREIKILE, reproducing the basic insert 66-86 of CK2 catalytic subunit, can mimick polylysine in triggering the latent "calmodulin kinase" activity of CK2 holoenzyme, and that spermine and, to a lesser extent, spermidine, but not putrescine, can reversibly and dose-dependently counteract such an activation. Spermine also abolishes the stimulation by polybasic peptides of basal CK2 activity. These findings disclose the possibility that spermine may act in vivo as a negative regulator of CK2 activity toward a category of substrates, like calmodulin and ornithine decarboxylase, whose phosphorylation is dependent on polybasic peptides.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/145921
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