Cubilin and AMN localization in single and doubly transfected CHO cells. (A) Confocal immunofluoresence microscopy of AMN and cubilin in permeabilized cells demonstrating colocalization of AMN and cubilin. Original magnification, × 630. (B) Surface staining of cubilin in cubilin single and cubilin/AMN double transfectants demonstrating absent surface expression in the cubilin single transfectants and punctuate surface expression in cubilin/AMN double transfectants. Original magnification, × 1000. (C) Immunogold staining of cubilin in cubilin single and cubilin/AMN double transfectants examined by electron microscopy demonstrating cubilin in the endocytic apparatus of double transfectants. Original magnification, × 46 000.