Micrographs and Western blots of extruded nuclei and reticulocytes. (A) Bright field illumination (top panels) and fluorescence microscopy (bottom panels) of an extruded nucleus from FVA cell culture, a PE-Ter119–labeled reticulocyte from FVA cell culture, and a PE-Ter119–labeled reticulocyte from bone marrow. Retic indicates reticulocyte. For scale reference, the diameter of the nucleus is 4.4 μm. (B) Nuclear and reticulocyte proteins from 5 × 105 nuclei and 5 × 105 reticulocytes from FVA cell cultures, separated on a SDS-PAGE gel, were immunoblotted using monoclonal antibody Ter119. Results from both fluorescence microscopy and Western blot analysis showed that GPA sorted predominantly to reticulocytes. (C) Nuclear and reticulocyte proteins from 5 × 105 nuclei and 5 × 105 reticulocytes from FVA cell cultures, separated on a SDS-PAGE gel, were immunoblotted using monoclonal antibodies specific for EMP or β1 integrin subunit. Both EMP and β1 partitioned predominantly to nuclei.
