PDEs catalytic domains

The regions outside the catalytic domain, particularly the amino terminus, are much more variable across the different PDE families. These regions contain many of the regulatory sites that control PDE activity (Fig. 21-6). For example, this region contains the Ca27calmodulin... 

PDEs are generally differentiated on the basis of their substrate specificity and how they are regulated. They consist of three main functional domains a regulatory C-terminus (probably involved in the actions of PDE-specific kinases), a central catalytic domain, and a regulatory N-terminus (involved in the allosteric regulation of substrate binding and phosphorylation and membrane targeting). 

Figure 9.2 Schematic representation of the domain structure of PDEs. The conserved catalytic domain is in the C-terminal portion (solid bars), whereas various regulatory domains make up the N terminus.

Cheung PP, Xu H, McLaughin MM, Ghazaleh FA, Livi GP, Colman RW. Human platelet cGI-PDE Expresaon in yeast and localization of the catalytic domain by deletion mutagenesis. Blood 88 1321-1329, 1996. 

All human PDEs are modular (Fig. 17.3) composed of a conserved C-terminal catalytic domain and various signal transduction domains that are thought to be sensors of intracellular signals, the reception of which leads to changes in conformation of the PDE and, thus, its activity (8). The catalytic domain contains a core of 16 g-helices ... 

---