A cDNA clone encoding a second type-2A protein phosphatase catalytic subunit (2Aβ) was isolated from a rabbit skeletal muscle cDNA library constructed in λgt10. The deduced protein sequence (309 residues, 35.59 kDa) was 97% identical to that of phosphatase 2Aα(309 residues, 35.58 kDa). At the nucleotide level, the two clones showed only 82% identity in the coding region. The results indicate the presence of at least two isoforms of protein phosphatase 2A in skeletal muscle.
