Irreversible oxidative inactivation of protein kinase C by photosensitive inhibitor calphostin C

FEBS Letters

Gopalakrishna, Rayudu¹  Gundimeda, Usha¹  Chen, Zhen Hai¹ 

[1] Department of Pharmacology and Nutrition, School of Medicine, University of Southern California, Los Angeles, CA 90033, USA

关键词: Protein kinase C;    Reactive oxygen species;    Singlet oxygen;    Calphostin C;    Oxidative modification;    Ca2+-induced hydrophobic region;    PKC;    protein kinase C;    EGTA;    ethylene glycol bis(β-aminoethylether)-N;    N′-tetraacetic acid;    PDBu;    phorbol 12;    13-dibutyrate;    TPA;    12-O-tetradecanoyl-phorbol 13-acetate;   

DOI  :  10.1016/0014-5793(92)80962-G

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Isolated protein kinase C (PKC) was irreversibly inactivated by a brief (min) incubation with calphostin C in the presence of light. This inactivation required Ca²⁺ either in a millimolar range in the absence of lipid activators or in a submicromolar range in the presence of lipid activators. In addition, an oxygen atmosphere was required suggesting the involvement of oxidation(s) in this inactivation process. Furthermore, PKC inactivation might involve a site-specific oxidative modification of the enzyme at the Ca²⁺-induced hydrophobic region. Physical quenchers of singlet oxygen such as lycopene, β-carotene, and α-tocopherol all reduced the calphostin C-induced inactivation of PKC. In intact cells treated with calphostin C, the inactivation of PKC was rapid in the membrane fraction compared to cytosol. This intracellular PKC inactivation was also found to be irreversible. Therefore, calphostin C can bring prolonged effects for several hours in cells treated for a short time. Taken together these results suggest that the calphostin C-mediated inactivation of PKC involves a site-specific and a ‘cage’ type oxidative modification of PKC.

【 授权许可】

Unknown