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 subuni t (B '' or delta) of human protein phosphatase 2A, were isolated. Thes e variants were identified from human cerebral cortex by library scree ning and PCR, and designated delta 1 and delta 3 isoforms, while the p reviously reported isoform [Tanabe et al. (1996) FEBS Lett. 379, 107-1 11] was designated delta 2. Compared with the delta 2 isoform, the del ta 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 iso form, and consisted of 496 amino acids. Using isoform-specific antipep tide antisera, the 74-kDa subunit (B '' or delta) originally purified from human erythrocytes mas identified as the delta 1 isoform. (C) 199 7 Federation of European Biochemical Societies.