Nuclear Lamina and the Structural Organization of the Nuclear Envelope

The nuclear envelope is a complex membrane organelle (for review, see Kay and Johnston 1973; Franke 1974; Fry 1976) that is involved in a number of diverse functional activities in the eukaryotic cell. Foremost, as the boundary that separates the nuclear and cytoplasmic compartments, this organelle appears to regulate the nucleocytoplasmic exchange of certain categories of macromolecules. Furthermore, the nuclear envelope may provide a structural anchoring site for other cellular components, including chromatin and cytoplasmic filaments. Finally, on the basis of its biochemical properties, the nuclear envelope appears, in part, to be functionally similar to membranes of the rough and smooth endoplasmic reticulum.