An unexpected structural relationship between integral membrane phosphatases and soluble haloperoxidases.

The mechanism of a membrane-bound enzyme important in phospholipid signaling, type 2 phosphatidic acid phosphatase, is suggested by sequence motifs shared with a soluble vanadium-dependent chloroperoxidase of known structure. These regions are also conserved in other soluble globular and membrane-associated proteins, including bacterial acid phosphatases, mammalian glucose-6-phosphatases, and the Drosophila developmental protein Wunen. This implies that a similar arrangement of catalytic residues specifies the active site within both soluble and membrane spanning domains.