Calcineurin plays an important role in the T-cell receptor-mediated signal transduction pathway. The protein encoded by this gene binds specifically to the activated form of calcineurin and inhibits calcineurin-mediated signal transduction. The encoded protein is found in the nucleus and contains a leucine zipper domain as well as several PEST motifs, sequences which confer targeted degradation to those proteins which contain them. Alternative splicing results in multiple transcript variants encoding two different isoforms. [provided by RefSeq, Jan 2011].