Nuclear pores: Difference between revisions
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Large molecules travel through the nuclear pores via [[Active transport|active transport]]. Some proteins such as [[Histones|histones]] are relatively small and can pass through the 9nm pores easily. However larger proteins, [[Ribosome|ribosomal subunits]] and [[MRNA|mRNA]] [[Molecules|molecules]] need another mechanism to pass through the [[Nuclear envelope|nuclear envelope]]. This is done via [[Active transport|active transport]]. [[Nuclear Localization Sequences|Nuclear Localization Sequences]] (NLS) on the cargo protein bind to a receptor [[Protein|protein]] called [[Importin|Importin]] to form an [[Importin-cargo complex|Importin-cargo complex]]. This complex is transported into the nucleus where the NLS releases the cargo protein and binds to a [[GTP|GTP]] binding protein called [[Ran|Ran]]. The resulting complex is transported out into the [[Cytoplasm|cytoplasm]] where the importin is recycled <ref>Becker, Kleinsmith, Hardin (2007), The World of the Cell (Published by Pearson Education Inc.), Chapter 18, The Structural Basis of Cellular Information pg 545-546</ref>. | Large molecules travel through the nuclear pores via [[Active transport|active transport]]. Some proteins such as [[Histones|histones]] are relatively small and can pass through the 9nm pores easily. However larger proteins, [[Ribosome|ribosomal subunits]] and [[MRNA|mRNA]] [[Molecules|molecules]] need another mechanism to pass through the [[Nuclear envelope|nuclear envelope]]. This is done via [[Active transport|active transport]]. [[Nuclear Localization Sequences|Nuclear Localization Sequences]] (NLS) on the cargo protein bind to a receptor [[Protein|protein]] called [[Importin|Importin]] to form an [[Importin-cargo complex|Importin-cargo complex]]. This complex is transported into the nucleus where the NLS releases the cargo protein and binds to a [[GTP|GTP]] binding protein called [[Ran|Ran]]. The resulting complex is transported out into the [[Cytoplasm|cytoplasm]] where the importin is recycled <ref>Becker, Kleinsmith, Hardin (2007), The World of the Cell (Published by Pearson Education Inc.), Chapter 18, The Structural Basis of Cellular Information pg 545-546</ref>. | ||
=== Structure === | === Structure === | ||
A proposed structure is Nup54, Nup58 and Nup62 make up the central channel for the [[Cell and membrane transport|transport]] of molecules from the [[Nucleus|nucleus]] through to the [[Cytoplasm|cytoplasm]]. It is thought that Nup54 and Nup58 form a ringed structure with which Nup62 then associates. The structure of the ring is flexible and the Nup62 and Nup58 complex interact with both the cytoplasmic and nucleoplasmic sides of the [[Nuclear envelope|nuclear envelope]] The diameter of the Nup 54/Nup58 ring regulates transport activity of molecules through the nuclear pores <ref>Solmaz SR, Chauhan R, Blobel G, Melčák I.. (2011). Molecular architecture of the transport channel of the nuclear pore complex.. Cell. 147 (3), 590-602</ref>. | |||
A proposed structure is Nup54, Nup58 and Nup62 make up the central channel for the[[ | |||
=== References === | === References === | ||
<references /> | <references /> | ||
Revision as of 14:42, 13 November 2011
Nuclear pores are large protein complexes that join the inner and the outer nuclear membranes to each other [1]. These pores allow the movement of mRNA out of the nucleus for translation.
Large molecules travel through the nuclear pores via active transport. Some proteins such as histones are relatively small and can pass through the 9nm pores easily. However larger proteins, ribosomal subunits and mRNA molecules need another mechanism to pass through the nuclear envelope. This is done via active transport. Nuclear Localization Sequences (NLS) on the cargo protein bind to a receptor protein called Importin to form an Importin-cargo complex. This complex is transported into the nucleus where the NLS releases the cargo protein and binds to a GTP binding protein called Ran. The resulting complex is transported out into the cytoplasm where the importin is recycled [2].
Structure
A proposed structure is Nup54, Nup58 and Nup62 make up the central channel for the transport of molecules from the nucleus through to the cytoplasm. It is thought that Nup54 and Nup58 form a ringed structure with which Nup62 then associates. The structure of the ring is flexible and the Nup62 and Nup58 complex interact with both the cytoplasmic and nucleoplasmic sides of the nuclear envelope The diameter of the Nup 54/Nup58 ring regulates transport activity of molecules through the nuclear pores [3].
References
- ↑ http://www.ks.uiuc.edu/Research/npc/
- ↑ Becker, Kleinsmith, Hardin (2007), The World of the Cell (Published by Pearson Education Inc.), Chapter 18, The Structural Basis of Cellular Information pg 545-546
- ↑ Solmaz SR, Chauhan R, Blobel G, Melčák I.. (2011). Molecular architecture of the transport channel of the nuclear pore complex.. Cell. 147 (3), 590-602