Phosphatidylserine (PS), an activator of protein kinase C (PKC) in the assay of protein phosphorylation, inhibited this enzyme in a time-dependent manner following preincubation in the absence of Ca2+. The phospholipid-induced inactivation of kinase activity was dependent on the PS content and on the charge density of liposomes. This inactivation of PKC could be reduced, but not completely eliminated, by addition of Ca2+. In the present work the effect of a naturally occurring polyamine (spermine) on the PS-induced inactivation of PKC was investigated. The presence of spermine during preincubation without Ca2+ was effective in suppressing the PS-induced inactivation of PKC over the period (20 min) required for PS to inhibit the enzyme by 95%. PKC exists in two membrane-bound states: a reversible one which can be dissociated by Ca2+ chelators (membrane-associated form) and an irreversible one which is chelator-stable (membrane-inserted form). Gel filtration experiments on the PKC-PS complex formed in the presence of Ca2+ indicated that less insertion of enzyme into liposomes occurred in the presence of spermine and that the kinase activity of the reversibly membrane-associated PKC was protected from PS inactivation.

Spermine protects protein kinase C from phospholipid-induced inactivation / Monti, Maria Giuseppina; S., Ghiaroni; Marverti, Gaetano; G., Piccinini; L., Pernecco; Moruzzi, Maria Stella. - In: EXPERIENTIA. - ISSN 0014-4754. - STAMPA. - 50:(1994), pp. 953-957.

Spermine protects protein kinase C from phospholipid-induced inactivation

MONTI, Maria Giuseppina;MARVERTI, Gaetano;MORUZZI, Maria Stella
1994-01-01

Abstract

Phosphatidylserine (PS), an activator of protein kinase C (PKC) in the assay of protein phosphorylation, inhibited this enzyme in a time-dependent manner following preincubation in the absence of Ca2+. The phospholipid-induced inactivation of kinase activity was dependent on the PS content and on the charge density of liposomes. This inactivation of PKC could be reduced, but not completely eliminated, by addition of Ca2+. In the present work the effect of a naturally occurring polyamine (spermine) on the PS-induced inactivation of PKC was investigated. The presence of spermine during preincubation without Ca2+ was effective in suppressing the PS-induced inactivation of PKC over the period (20 min) required for PS to inhibit the enzyme by 95%. PKC exists in two membrane-bound states: a reversible one which can be dissociated by Ca2+ chelators (membrane-associated form) and an irreversible one which is chelator-stable (membrane-inserted form). Gel filtration experiments on the PKC-PS complex formed in the presence of Ca2+ indicated that less insertion of enzyme into liposomes occurred in the presence of spermine and that the kinase activity of the reversibly membrane-associated PKC was protected from PS inactivation.
50
953
957
Spermine protects protein kinase C from phospholipid-induced inactivation / Monti, Maria Giuseppina; S., Ghiaroni; Marverti, Gaetano; G., Piccinini; L., Pernecco; Moruzzi, Maria Stella. - In: EXPERIENTIA. - ISSN 0014-4754. - STAMPA. - 50:(1994), pp. 953-957.
Monti, Maria Giuseppina; S., Ghiaroni; Marverti, Gaetano; G., Piccinini; L., Pernecco; Moruzzi, Maria Stella
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/306063
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