Molecular heterogeneity of the cDNA encoding a 74-kDa regulatory subunit (B'' or delta) of human protein phosphatase 2A

Two cDNAs for possible splicing variants of a 74-kDa regulatory subunit (B '' or delta) of human protein phosphatase 2A, were isolated. These variants were identified from human cerebral cortex by library screening and PCR, and designated delta 1 and delta 3 isoforms, while the previously reported isoform [Tanabe et al. (1996) FEBS Lett. 379, 107-111] was designated delta 2. Compared with the delta 2 isoform, the delta 1 isoform contained a 32-residue insertion beginning at residue 84, and consisted of 602 amino acids in all. The delta 3 isoform lacked a 74-residue sequence corresponding to residues 1083 of the delta 2 isoform, and consisted of 496 amino acids. Using isoform-specific antipeptide antisera, the 74-kDa subunit (B '' or delta) originally purified from human erythrocytes mas identified as the delta 1 isoform. (C) 1997 Federation of European Biochemical Societies.