Nuclear envelope


Nuclear envelope
Human cell nucleus

A nuclear envelope (NE) (also known as the perinuclear envelope, nuclear membrane, nucleolemma or karyotheca) is a double lipid bilayer that encloses the genetic material in eukaryotic cells. The nuclear envelope also serves as the physical barrier, separating the contents of the nucleus (DNA in particular) from the cytosol (cytoplasm). Many nuclear pores are inserted in the nuclear envelope, which facilitate and regulate the exchange of materials (proteins such as transcription factors, and RNA) between the nucleus and the cytoplasm.

Each of the two membranes is composed of a lipid bilayer. The outer membrane is continuous with the rough endoplasmic reticulum while the inner nuclear membrane is the primary residence of several inner nuclear membrane proteins. The outer and inner nuclear membrane are fused at the site of nuclear pore complexes. The structure of the membrane also consists of ribosomes.

The three layers of NE proteins. The nuclear pore complex (NPC) transverses the inner and outer nuclear membranes. Perinuclear space is clearly visible. INM proteins, including SUN1, LAP2, Emerin, MAN1 and LBR, are mostly associated with the nuclear lamina. Emerin, LAP2 and MAN1 harbor a LEM domain which interacts with BAF (barrier-to-autointegration factor), a chromatin-binding protein. The nuclear lamina forms a meshwork underlying the inner nuclear membrane. Chi et al. Journal of Biomedical Science 2009.[1]

The inner nuclear membrane is connected to the nuclear lamina, a network of intermediate filaments composed of various lamins (A, B1, B2, & C). The lamina acts as a site of attachment for chromosomes and provides structural stability to the nucleus. The lamins have been associated with various genetic disorders collectively termed laminopathies.

The space between the two membranes that make up the nuclear envelope is called the perinuclear space (also called the perinuclear cisterna, NE Lumen), and is usually about 20 - 40 nm wide.

The nuclear envelope has been postulated to play a role in the organization and transcriptional activity of chromatin.

References

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • nuclear envelope — the structure enclosing the cell nucleus and separating it from the cytoplasm, consisting of two concentric lipid bilayers (the inner and outer membranes) separated by a 30 nm wide perinuclear space. The outer membrane is continuous with the… …   Medical dictionary

  • nuclear envelope — branduolio apvalkalėlis statusas T sritis augalininkystė apibrėžtis Dviguba membrana, atskirianti ląstelės branduolį nuo citoplazmos. atitikmenys: angl. nuclear envelope rus. ядерная оболочка …   Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas

  • nuclear envelope — Membrane system that surrounds the nucleus of eukaryotic cells. Consists of inner and outer membranes separated by perinuclear space and perforated by nuclear pores. The term should be used in preference to the term nuclear membrane which is… …   Dictionary of molecular biology

  • nuclear envelope — noun see nuclear membrane …   New Collegiate Dictionary

  • nuclear envelope — Double layered membrane separating the nucleoplasm from the cytoplasm; nuclear membrane …   Dictionary of invertebrate zoology

  • nuclear envelope — (nu kle ar) The complex double membrane structure forming the outer boundary of the eucaryotic nucleus. It is covered by pores through which substances enter and leave the nucleus …   Dictionary of microbiology

  • nuclear membrane — n a double membrane enclosing a cell nucleus and having its outer part continuous with the endoplasmic reticulum called also karyotheca * * * 1. either of the membranes, inner and outer, comprising the 2. nuclear envelope. nuclear envelope …   Medical dictionary

  • nuclear membrane — n. the double layered membrane of the nucleus of a cell, separating the nucleoplasm from the cytoplasm, that is permeable to certain molecules, esp. DNA, RNA, and ATP: now often nuclear envelope …   English World dictionary

  • Nuclear lamina — The nuclear lamina is a dense ( 30 to 100 nm thick) fibrillar network inside the nucleus of a eukaryotic cell. It is composed of intermediate filaments and membrane associated proteins. Besides providing mechanical support, the nuclear lamina… …   Wikipedia

  • Nuclear pore — Diagram of human cell nucleus. Nuclear pore labeled at bottom left …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.