What is the Nuclear Envelope?
The nuclear envelope is composed of the nuclear membranes, the nuclear
lamina and the nuclear pore complexes. The nuclear membranes are divided
into three morphologically distinct but interconnected domains termed the
inner nuclear membrane, outer nuclear membrane and pore membrane. Each
of these membrane domains is associated with specific macromolecular
structures. Ribosomes, that are also present on the continuous
endodplasmic reticulum, are associated with the outer face of the outer
nuclear membrane. The nuclear pore complexes, macromolecular structures
through which transport between the nucleus and cytoplasm takes place,
are associated with the pore membranes. The inner nuclear membrane is
associated with the nuclear lamina, a meshwork of intermediate filament
proteins termed lamins, and the heterochromatin on its nucleoplasmic
face. In recent years, mutations in nuclear lamins have been shown to
cause muscular dystrophy, cardiomyopathy and partial lipodystrohy.
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Nuclear envelope/Howard J. Worman, M. D./hjw14@columbia.edu