Alignment of catalytic region and site-directed mutants in 3 PDEs.

Alignment of part of the conserved domains of deduced amino acid sequences of members of 3 PDE families with the invariate histidine and glutamate residues that are likely to form ligands to the metal ion. The bold font indicates mutants of PDE3A from our laboratory (this report and Cheung et al26), mutants of PDE4A,23and mutants of PDE5.24