The single transmembrane segment of gp210 is sufficient for sorting to the pore membrane domain of the nuclear envelope

To distinguish the expression of recombinant from endogenous gp210, we inserted an epitope tag encoding 12-amino acid residues of HA (8, 34) after the second residue of the mature form of gp210 (see Fig. 1 ). Using an mAb against the tag (anti-HA antibody), the expressed gp210:HA showed the punctate distribution at the nuclear surface (Fig. 2 A) that is characteristic for endogenous gp210 in the pore membrane (6) . To further substantiate the localization of gp210:HA in (mAb 414, B) . The focal plane shown in A and B is tangential to the nuclear surface, gp210:HA is visible at densely packed points along the surface of the nucleus and, to a much lesser extent, in a dispersed pattern in the cytoplasm. Note the extensive coincidence between this pattern and the NPC pattern shown in B. Bar, 10 #m.