Molecular cloning in Arabidopsis thaliana of a new protein phosphatase 2C (PP2C) with homology to ABI1 and ABI2

We report the cloning of both the cDNA and the corresponding genomic sequen ce of a new PP2C from Arabidopsis thaliana, named AtP2C-HA (for homology to ABI1/ABI2). The AtP2C-HA cDNA contains an open reading frame of 1536 bp an d encodes a putative protein of 511 amino acids with a predicted molecular mass of 55.7 kDa. The AtP2C-HA protein is composed of two domains, a C-term inal PP2C catalytic domain and a N-terminal extension of ca. 180 amino acid residues. The deduced amino acid sequence is 55% and 54% identical to ABI1 and ABI2, respectively. Comparison of the genomic structure of the ABI1, A BI2 and AtP2C-HA genes suggests that they belong to a multigene family. The expression of the AtP2C-HA gene is up-regulated by abscisic acid (ABA) tre atment.