Colocalization of emerin and lamins in interphase nuclei and changes during mitosis

Emerin is a nuclear membrane protein which is affected by mutation in X-linked Emery-Dreifuss muscular dystrophy. We have previously suggested that emerin is a member of a family of type II integral membrane proteins which associate with the nuclear lamina and which include lamina-associated proteins and the lamin B receptor. We now show that emerin in COS cells is not restricted to the nuclear rim but is also found at intranuclear sites, where it colocalizes with nuclear lamins B1, B2 and A/C. During mitosis, emerin is dispersed throughout the cell and then participates in the reconstitution of membranes around the daughter nuclei. Although emerin and lamins do not remain colocalized during mitosis, they all show some association with the midbody of the mitotic spindle.