In vitro enzyme activation with calbindin‐D28k, the vitamin D‐dependent 28 kDa calcium binding protein

FEBS Letters

Vanaman, Thomas C.¹  Reisner, Peter D.¹  Christakos, Sylvia² 

[1] Department of Biochemistry, University of Kentucky College of Medicine, and L. P. Markey Cancer Center, Lexington, KY 40536, USA;Department of Biochemistry, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA

关键词: Calbindin;    Ca2+-ATPase;    Phosphodiesterase;    Calmodulin;    Enzyme activation;    CaBP-D28k;    calbindin-D28k;    CaBP-D9k;    calbindin-D9k;    CaM;    Calmodulin;    PDE;    phosphodiesterase;    EGTA;    ethylene glycol bis-(β-aminoethyl ether) N;    N;    N′;    N′-tetraacetic acid;    HEPES;    N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid;    SDS;    sodium dodecyl sulfate;    PAGE;    polyacrylamide gel electrophoresis;   

DOI  :  10.1016/0014-5793(92)80342-E

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Purified porcine erythrocyte membrane Ca²⁺-ATPase and 3′:5′-cyclic nucleotide phosphodiesterase were stimulated in a dose-dependent, saturable manner with the vitamin D-dependent calcium binding protein from rat kidney, calbindin-D_28k (CaBP-D_28k). The concentration of CaBP-D_28k required for half-maximal activation (K _0.5 act.) of the Ca²⁺-ATPase was 28 nM compared to 2.2 nM for calmodulin (CaM), with maximal activation equivalent upon addition or either excess CaM or CaBP-D_28k, 3′:5′-Cyclic nucleotide phosphodiesterase (PDE) also showed equivalent maximum saturable activation by calbindin (K _0.5 act. = 90 nM) or calmodulin (K _0.5 act. = 1.2 nM). CaBP-D_28k was shown to effectively compete with CaM-Sepharose for PDE binding. Immunoprecipitation with CaBP-D_28k antiserum completely inhibited calbindin-mediated activation of PDE but had no effect on calmodulin's ability to activate PDE. While the physiological significance of these results remains to be established, they do suggest that CaBP-D_28k can activate enzymes and may be a regulator of yet to be identified target enzymes in certain tissues.

【 授权许可】

Unknown