nuclear membranes
The nuclear envelope is composed of the nuclear lamina, the nuclear pore complexes, and the nuclear membranes.
The nuclear lamina is a discontinuous structure that occupies only a fraction of the nuclear periphery, and at some points, the inner nuclear membrane may interact directly with the chromatin.
The nuclear membranes can be divided into 3 morphologically distinct but interconnected domains: the outer nuclear membrane, the inner nuclear membrane, and the nuclear pore membrane.
- The inner nuclear membrane is adjacent to the nuclear lamina, a meshwork of intermediate filament proteins termed lamins.
- Several integral proteins of the nuclear envelope inner membrane that may be associated with the lamina and the chromatin have been identified. The first was a protein called lamin B receptor (LBR) that binds in vitro to lamin B.
To enter the nucleus a protein must be chaperoned by a transport factor through the nuclear pore complex or it must be small enough to pass through by diffusion.
References
Lusk CP, Blobel G, King MC. Highway to the inner nuclear membrane: rules for the road. Nat Rev Mol Cell Biol. 2007 May;8(5):414-20. PMID: 17440484