The RCAN carboxyl end mediates calcineurin docking-dependent inhibition via a site that dictates binding to substrates and regulators.
Martinez-Martinez S, Genesca L, Rodriguez A, Raya A, Salichs E, Were F, Lopez-Maderuelo MD, Redondo JM, de la Luna S, Proc Natl Acad Sci U S A, 2009 Apr 14 - link