Fig. 1

a (i) Schematic of PDE4B isoforms. The long isoforms PDE4B1, PDE4B3, and PDE4B4 contain the catalytic domain, UCR1 and UCR2, plus isoform-specific unique regions at their amino-termini. The short isoform PDE4B2 contains the catalytic domain and UCR2, while the super-short PDE4B5 isoform contains the catalytic region and a portion of UCR2. UCR1 and UCR2 mediate dimerization of the long PDE4B isoforms. Also shown are the carboxyl-terminal region common to all PDE4B isoforms, the PKA site located within UCR1, and the location of D564, the amino acid mutated in this study. (ii) Structure of PDE4B1 with the D564A mutation that is expressed in the transgenic mice. b Expression of the PDE4B1-D564A transgene. (i) Characterization of the PDE4B1 antibody. Extracts from COS7 cells transfected to express PDE4B1-VSV were immunoblotted with an antibody against VSV or against PDE4B1; both antibodies detected a protein of identical mobility, of 95 kDa. (ii) Immunoblotting of brain lysates from wild-type mice with the PDE4B1 antibody identified endogenous PDE4B1 (95 kDa). Lysates from PDE4B1-D564A transgenic mice also expressed a band of slightly slower mobility, representing the protein encoded by the PDE4B1-D564A transgene (96 kDa), in addition to endogenous PDE4B1 (95 kDa). Immunoblotting with GAPDH was used a loading control. The amount of extract protein loaded per lane is given at the bottom of each lane