Protein phosphatase 2A: identification in Oryza sativa of the gene encoding the regulatory A subunit

A 2225 bp cDNA, designated RPA1, was isolated from an Oryza sativa cDNA lib rary. Analysis revealed a 1761 bp coding sequence with 15 non-identical rep eat units. The ORF encoded the A regulatory subunit of protein phosphatase 2A (PP2A-A) as ascertained by complementation of the yeast tpd3 mutant defe ctive in this gene. The corresponding genomic DNA from a rice genome BAC li brary revealed that the gene contains eleven introns. The rice genome conta ins only a single copy of this gene as judged by Southern blot analysis. Th e PP2A protein is highly conserved in nature; the rice protein shows 88% am ino acid identity with its counterparts in Arabidopsis or Nicotiana tabacum .