Fig. 2. Expression of MAGI-3 mRNA and protein. (A) A northern blot containing mRNA from various rat tissues hybridized with a DNA fragment containing the third and fourth PDZ domains of MAGI-3 as a probe. The autoradiogram is shown along with the location of molecular weight markers in kb. A single 6.4 kb transcript was detected in the indicated tissues. (B) RT-PCR analyses peformed with MAGI-3-specific primers on the indicated rat tissues, GH3 neuroendocrine cell line, neuronal stem cells (NSC) and primary astrocytes. MAGI-3 cDNA (MAGI-3) and a reaction containing no DNA (—DNA) were used as positive and negative controls, respectively. (C) Expression of MAGI-3 protein in various cell lines. Cell lysates made from the indicated cell lines or primary astrocytes were subjected to immunoprecipitation and western blot analysis using an antibody to MAGI-3. Molecular weight markers in kDa are shown on the right. Note that the lower two bands shown in C6 are degradation products of MAGI-3, which were not detected in other experiments. (D) Rat brain membrane lysates were immunoprecipitated with specific antibodies to MAGI-3 or with the preimmune serum (PI) as indicated, followed by immunoblotting with anti-MAGI-3 antibody.