2. The nuclear envelope is perforated with tiny holes
known as nuclear pores, which were first
discovered in the mid-twentieth century.
These pores regulate the passage of molecules
between the nucleus and cytoplasm, permitting
some to pass through the membrane but not
others.
DNA and RNA is formed within nucleus and
ribosomal sub units in the nucleosomes must
leave the nucleus.
3. Nuclear pores are fully permeable to small
molecules up to the size of the smallest proteins
but form a barrier keeping most large molecules
out of the nucleus.
larger proteins, such as histones, are granted
admission into the nucleus despite the fact that the
pores should be too small to let them through.
It is generally thought that the elaborate protein
structure called the nuclear pore complex.
4. What are NPC?
The nuclear pore complex is comprised of several
subunits
Surrounding the inside of the pore is a
nonmembranous material organized into an
annulus that extends spoke-like structures toward
the center of the small channel.
The actual pore wall is predominantly comprised
of columnar subunits, and lumenal subunits, with
the help of transmembrane proteins, anchor the
entire pore complex into the nuclear envelope.
5.
6. Also, tiny fibrils usually extend form both sides of
the complex and congregate into basket-like
configurations on the nuclear side of the complex.
The proteinaceous composition of these fibrils is
different on opposing sides of the structure.
Functions:
1) Various proteins and other molecules
need to enter or exit the nucleus in order
to perform their functions. Once a messenger
RNA (mRNA) has been synthesized in the
nucleus, for example, it needs to travel out into
the cell, where it can be used to make a protein.
7. 2.) Nuclear pores regulate this traffic to ensure
that only some molecules can enter and exit the
nucleus of the cell.
3) nuclear pores are important as sites where
the outer membrane and inner membrane of the
nuclear envelope are fused together.
