A novel, calcium‐inhibitable casein kinase in Paramecium cells

FEBS Letters

Treptau, Tilman¹  Kissmehl, Roland¹  Hauser, Karin¹  Plattner, Helmut¹ 

[1]Faculty of Biology, University of Konstanz, P.O. Box 5560, D-78434 Konstanz, Germany

关键词: Calcineurin;    Calmodulin;    Casein kinase;    Exocytosis;    Paramecium;    Phosphorylation;    CaM;    calmodulin;    CaN;    calcineurin or protein phosphatase-2B;    CaN A;    catalytic subunit of CaN;    CaN B;    regulatory subunit of CaN;    CPK;    casein kinase isolated from P. tetraurelia;    CK-1;    type 1 casein kinase;    CK-2;    type 2 casein kinase;    HM;    homogenization medium;    PAGE;    polyacrylamide gel electrophoresis;    PKA;    cAMP-dependent protein kinase;    PKG;    cGMP-dependent protein kinase;    PLA;    poly(l-arginine);    PLL;    poly(l-lysine);    PP63;    exocytosis-sensitive phosphoprotein of 63 kDa;    SP;    spermine;    TAME;    N-p-tosyl-l-arginine methyl ester;   

DOI  :  10.1016/S0014-5793(96)01539-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

This is the first identification of a Ca²⁺-inhibitable casein kinase (CPK) which we have isolated from the 100 000×g supernatant of Paramecium cell homogenates. The 1000-fold enriched CPK activity depends on millimolar Mg²⁺ and is inhibited by low concentrations of heparin or by ≥100 μM Ca²⁺. Enzyme activity is stimulated by polylysine or polyarginine with either casein or with specific casein kinase-2 (CK-2) peptide substrates (RRRDDDSDDD and RREEETEEE). The enzymic properties are similar with GTP instead of ATP. CPK does not undergo autophosphorylation. In gel kinase assays, enzyme activity is associated with a 36 kDa band. Calmodulin as another characteristic substrate for mammalian CK-2 has not been phosphorylated by this protein kinase. Besides casein, CPK phosphorylates in vitro the catalytic subunit of bovine brain calcineurin (CaN), a typical substrate of type 1 mammalian casein kinase (CK-1) in vitro. Again this phosphorylation is significantly reduced by Ca²⁺. Thus, CPK combines aspects of different casein kinases, but it is clearly different from any type known by its Ca²⁺ inhibition. Since CPK also phosphorylates the exocytosis-sensitive phosphoprotein, PP63, in Paramecium, which is known to be dephosphorylated by CaN, an antagonistic Ca²⁺-effect during phosphorylation/dephosphorylation cycles may be relevant for exocytosis regulation.

【 授权许可】

Unknown