Nuclear pore
hideNuclear pores are large protein complexes that cross the nuclear envelope, which is the double membrane surrounding the eukaryotic cell nucleus. There are about on average 2000 nuclear pore complexes in the nuclear envelope of a vertebrate cell, but it varies depending on cell type and throughout the life cycle. The proteins that make up the nuclear pore complex are known as nucleoporins. About half of the nucleoporins typically contain either an alpha solenoid or a beta-propeller fold, or in some cases both as separate structural domains. The other half show structural characteristics typical of "natively unfolded" proteins, i.e. they are highly flexible proteins that lack ordered secondary structure. These disordered proteins are the FG nucleoporins, so called because their amino-acid sequence contains many repeats of the peptide phenylalanine—glycine.
Nuclear pores allow the transport of water-soluble molecules across the nuclear envelope. This transport includes RNA and ribosomes moving from nucleus to the cytoplasm and proteins (such as DNA polymerase and lamins), carbohydrates, signal molecules and lipids moving into the nucleus. It is notable that the nuclear pore complex (NPC) can actively conduct 1000 translocations per complex per second. Although smaller molecules simply diffuse through the pores, larger molecules may be recognized by specific signal sequences and then be diffused with the help of nucleoporins into or out of the nucleus. This is known as the RAN cycle. Each of the eight protein subunits surrounding the actual pore (the outer ring) projects a spoke-shaped protein into the pore channel. The center of the pore often appears to contains a plug-like structure. It is yet unknown whether this corresponds to an actual plug or is merely cargo caught in transit.
For more information about Nuclear pore, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with nuclear pore
Biologists reveal structure of cell nucleus 'gatekeeper'
Oct 27, 2009 |
4 / 5 (5) |
6
(PhysOrg.com) -- Biologists led by associate professor Thomas Schwartz (MIT) have worked out a rudimentary architectural plan for the nuclear pore complex (NPC), the gatekeeper of the cell's nucleus.
Researchers construct a device that mimics one of nature's key transport machines
Biology /
Jan 06, 2009 |
4.7 / 5 (7) |
0
(PhysOrg.com) -- To help protect its genes, a cell is highly selective about what it allows to move in and out of its nucleus. Yet that choosiness is regulated by just a thin barrier, perforated with tiny ...
'Promiscuous' protein interactions found in the nuclear pore complex
Sep 29, 2009 |
5 / 5 (1) |
0
(PhysOrg.com) -- The NPC is the only way in or out of a cell's nucleus. It plays a key role in cellular metabolism and signaling, and any malfunction in these pores can have lethal consequences. Now new research reveals further ...
New research supports model for nuclear pore complex
Aug 18, 2009 |
not rated yet |
0
(PhysOrg.com) -- To protect their DNA, cells in higher organisms are very choosy about what they allow in and out of their nuclei, where the genes reside. Guarding access is the job of transport machines called nuclear pore ...
Research identifies 3-D structure of key nuclear pore building block
Jun 07, 2009 |
5 / 5 (1) |
0
The genome of complex organisms is stashed away inside each cell's nucleus, a little like a sovereign shielded from the threatening world outside. The genome cannot govern from its protective chamber, however, without knowing ...
The breakdown of barriers in old cells may hold clues to aging process
Biology /
Jan 22, 2009 |
5 / 5 (3) |
0
Like guards controlling access to a gated community, nuclear pore complexes are communication channels that regulate the passage of proteins and RNA to and from a cell's nucleus. Recent studies by researchers ...
Come on in: Nuclear barrier less restrictive than expected in new cells
Oct 06, 2009 |
not rated yet |
0
When it comes to the two basic types of cells, prokaryotes and eukaryotes, compartmentalization is everything. Prokaryotes are evolutionarily ancient cells that only have a membrane surrounding their outer boundary, while ...
Research suggests core nuclear pore elements shared by all eukaryotes
Jul 13, 2009 |
5 / 5 (1) |
0
(PhysOrg.com) -- For perhaps 1.8 billion years after life first emerged on Earth, a sort of evolutionary writer’s block stalled the development of organisms more complicated than single cells. Then, a burst of experimental ...
Structural study backs new model for the nuclear pore complex
Biology /
Dec 24, 2008 |
4.5 / 5 (2) |
0
(PhysOrg.com) -- In higher organisms, the genetic material is confined and protected in the cell nucleus. In order for a healthy cell to function, the DNA must send manufacturing orders through the double ...
Solving the Nuclear Pore Puzzle
Aug 19, 2009 |
not rated yet |
0
(PhysOrg.com) -- Computational biochemist Frank Alber compares determining the architecture of a macromolecular machine to solving a jigsaw puzzle.
