Isoform 2 may act as a competitive inhibitor of calmodulin-dependent enzymes such as calcineurin in neurons. Interacts with CALM1. Isoform 2 is expressed in brain. Isoform 1 is present in immature thymocytes (at protein level). Phosphorylation at Ser-56 favors interaction with CALM1. Isoform 1 is methylated by CARM1 at Arg-655 in immature thymocytes.