| Popis: |
The nuclear pore complex (NPC) mediates the nucleocytoplasmic transport through the nuclear envelope. It is a supramolecular, cylindrical structure with an overall diameter of ~130 nm, a thickness ~ 70 nm (Akey, 1989) and a molecular mass of 125 MDa (Reichelt et al. 1990). The pore consists of two concentric rings on the inner and outer face of the nuclear membrane, eight radial spokes and a central plug (Unwin and Milligan, 1982; Reichelt et al. 1990; Jarnik and Aebi, 1991). Recent EM studies revealed, besides a central channel, eight smaller peripheral channels with a diameter of 10 nm which could be used for diffusion of small molecules (Hinshaw et al. 1992). The NPC is associated with cytoskeletal structures: a basketlike network at the nucleoplasmic side and fibrillar elements directing into the cytoplasm (Akey, 1989; Reichelt et al. 1990). |
