| Selective interaction of megalin with postsynaptic density 95 ( PSD 95 ) like membrane associated guanylate kinase ( MAGUK ) proteins . ^^^ Using interaction cloning in yeast , we identified the membrane associated guanylate kinase family member postsynaptic density 95 ( PSD 95 ) as an interaction partner for megalin . ^^^ PSD 95 and a truncated version of megalin were co immunoprecipitated from HEK 293 cell lysates overexpressing the two proteins , which confirmed the interaction . ^^^ Immunocytochemical studies showed that cells in the parathyroid , proximal tubuli of the kidney and placenta express both megalin and PSD 95 . ^^^ We found that the interaction between the two proteins is mediated by the binding of the C terminus of megalin , which has a type 1 PSD 95 / Drosophila discs large / zona occludens 1 ( PDZ ) binding motif , to the PDZ 2 domain of PSD 95 . ^^^ |