Analysis Note

Sigma tests activity in 80 mM Tris, pH 7.5 with 65 mM KCl, 8 mM MgSO₄ and 0.3% albumin.

Application

Calcineurin from bovine brain has been used: as a positive control in western blot analysis of oocytes and cumulus cells proteomeas a positive control in calmodulin (CaM)-agarose binding assay to test its phosphatase activity in the presence of okadaic acid

Biochem/physiol Actions

Calcineurin (CaN) activity is stimulated by nickel (Nⁱ²⁺) and manganese (Mn²⁺) ions. It participates in the coupling of Ca²⁺ signals. CaN may regulate oocyte growth and meiotic maturation in porcine. It also participates in gene regulation, cell survival, and death.

Calcineurin is a cyclosporin-sensitive, calcium-regulated, serine-threonine protein phosphatase with broad substrate specificity. It is the major calmodulin-binding protein found in the brain. First identified as an inhibitor of the calmodulin activation of phosphodiesterase 3′:5′ cyclic nucleotide (PDE), calcineurin has similar effects on adenylate cyclase. Serves as a key enzyme involved in T-cell activation. Also involved in the hyperphosphorylation of tau protein in Alzheimer′s disease and has been shown to prevent calpain-mediated proteolysis of tau in differentiated PC12 cells.

General description

Calcineurin (CaN) comprises CaN A and CaN B subunits. It exists as a heterodimer with a calmodulin-binding domain, catalytic site, a CaN B binding domain, and an autoinhibitory domain.

Physical form

Lyophilized powder containing 0.5% EGTA, buffer salts and stabilizers.

Unit Definition

One unit will cause a 50% inhibition of the activated phosphodiesterase, 3′:5′-cyclic nucleotide (P 9529) activity when assayed with two units of activator (P 2277) and 0.1 mM Ca²⁺ in an enzyme coupled system at pH 7.5 at 30 °C.