well as amino acids that lie N-terminal to calcineurin's autoinhibitory domain [Figure 2(B)]. CNEX3-12 skips exon 4-11. The resultant 274 amino acid deletion removes both phosphatase catalytic and subunit B binding domains [Figure 2(B)]. More than two dozens of calcineurin isoforms can thus be formed by these alternative-splicing events. CNEX1-3, 1-4, 13-14, and 13-15 isoforms have been previously described (Guerini and Klee, 1989; Kincaid et al., 1990; Reuter, Mi, Sehrsam, Ludolph, & Volkel, 2001). CNEX1-2, 1-10, 3-12, and 9-11 isoforms are reported here for the first time.
