The nuclear envelope consists of octagonal pores. These pores are called nuclear pores. Nuclear membrane has 300 pores. The number of nuclear pores per square micrometer is 40-145. The hole-to-hole distance is 1500 Å. The diameter of each pore is 9 nm. The pores are constricted and expanded by a protein network.
The nuclear pore contains the annulus. The annulus contains 8 granular edge proteins. Peripheral proteins are linked by spokes. At the center of the nuclear pore is a large protein called a transporter. The transporter is attached to the envelope by anchor proteins. Proteins can consist of subunits and fibers. Inside the nucleus is a fibrous cage. Proteins are attached to the fiber cage. Peripheral proteins associate with the transporter to form a wheel-like structure.
Function: It maintains contact with the cytoplasm and transports materials. The product passes through the nuclear pores into the cytoplasm.