FIGURE 3.

Diagram of the domain structure of the kinetoplastid PDEs. The conserved catalytic domain is the main functional domain of the PDEs and binds cAMP. The GAF-A domains of PDEB1 and B2 bind cAMP and cGMP and regulate the function of the catalytic domain (Laxman et al., 2005). FYVE finger has been shown to bind two Zn²⁺ ions. Coiled-coil domains are important in stabilizing protein structure and thus for protein function. Phosphorylation of the indicated serine residues of PDEB1 has been observed in the T. brucei phosphoproteome (Nett et al., 2009) whilst a probably functionally conserved PKA phosphorylation site is predicted in PDEB1/B2 (Shakur et al., 2011).