The catalytic domain of the P-type ATPase has the haloacid dehalogenase fold

The P-type ATPases belong to a superfamily of hydrolases whose structure is typified by the L-2-haloacid dehalogenase (HAD) 7,8 from Pseudomonas sp. The catalytic mechanism of P-type ATPases and HAD 7,8 are similar, providing clues to the evolution of these enzymes. The catalytic domain of P-type ATPases has been found to have the structural fold of haloacid dehalogenases. Thus, P-type ATPases might have evolved by fusion of a transmembrane protein with a HAD superfamily phosphatase domain.