May act as a competitive inhibitor of calmodulin-dependent enzymes such as calcineurin in neurons. Interacts with CALM1. Present at high levels in thymus and low levels in brain. In thymus, isoform 1 is specifically found in immature thymocytes (at protein level). Down-regulated in thymocytes upon TCR engagement (at protein level). Phosphorylation of isoform 2 at Ser-55 is enhanced upon dopamine D1 receptor activation and favors interaction with CALM1. Methylated by CARM1 at Arg-650 in immature thymocytes. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay.