Fig. 3. Indirect immunofluorescence analysis of HA-tagged lamin A alleles expressed in HeLa cells. Intranuclear aggregates induced by HA-LaA N195K (C) invariably contain lamin B2 (D, LaB2). In nontransfected cells both lamin A (A) and lamin B2 (B) are concentrated at the nuclear periphery (B). In A-D, the cells were double labeled with a rabbit antibody against lamin A and a mouse monoclonal antibody against lamin B2. In E-I the cells were labeled with the 12CA5 anti-HA antibody. The high-magnification views in E-G reveal that, in contrast to wild-type lamin A (LaA, E), LaA L85R (F) is distributed in a speckled pattern across the nuclear surface. Numerous small intranuclear aggregates formed by the LaA N195K mutant (G) is also shown. The difference in distribution between wild-type lamin A (H) and LaA L85R (I) is further demonstrated by confocal images of the equatorial region of a pair of nuclei. A more continuous labeling pattern is observed with wild-type lamin A than with LaA L85R.