| GAIP , GIPC and Galphai 3 are concentrated in endocytic compartments of proximal tubule cells : putative role in regulating megalin ' s function . ^^^ By immunofluorescence GIPC and GAIP , components of G protein mediated signaling pathways , are also concentrated in the brush border region of PTE and are present in megalin expressing cell lines . ^^^ In precipitation assays , GST GIPC specifically binds megalin . ^^^ The concentration of Galphai 3 , GIPC , and GAIP with megalin in endocytic compartments of the proximal tubule , where extensive endocytosis occurs , and the interaction between GIPC and the cytoplasmic tail of megalin suggest a model whereby G protein mediated signaling may regulate megalin ' s endocytic function and / or trafficking . . ^^^ |