Identification of protein-tyrosine phosphatases in Archaea

Protein-tyrosine dephosphorylation is a major mechanism in cellular regulat ion, A large number of protein-tyrosine phosphatases is known from Eukarya, and more recently bacterial homologues have also been identified, By emplo ying conserved sequence patterns from both eukaryotic and bacterial protein -tyrosine phosphatases, we have identified three homologous sequences in tw o of the four complete archaeal genomes. Two hypothetical open reading fram es in the genome of Methanococcus jannnschii (MJ0215 and MJECL20) and one i n the genome of Pyrococcus horikoshii (PH1732) clearly bear all the conserv ed residues of this family. No homologues were found in the genomes of Arch aeoglobus fulgidus and Methanobacterium thermoautotrophicum. This is the fi rst report of protein-tyrosine phosphatase sequences in Archaea.