Revised Manuscript Received September 9, 1987 abstract: Clones coding for the catalytic subunit of one of the major protein phosphatases (type 2A) were isolated from a porcine cDNA library. Sequence analysisindicated that two different mRNA species coded for this enzyme. The deduced amino acid sequences of the two forms (a and/3) of the enzyme were 98% identical and showed 95% identity with the partial sequence of the rabbit enzyme determined by amino acid sequencing. The use of specific oligonucleotide probes indicated that the mRNAs coding for the a and $ forms were about 2 kilobases in length, present in equal amounts in a porcine cell line (LLC-PK!), and were the products of two distinct genes. Southern analysis using the coding region of the a phosphatase cDNA as a probe suggested the existence of additional related phosphatase genes.