title: Structural features of transversal barrier in central channel of nuclear pore complex.
abstract: The most important entity of the selective behavior of the nuclear pore complex (NPC) is considered to be the matter called "barrier," "meshwork" or "sieve." This part of NPC has not been well elucidated by using electron microscopy methods to date. In the present study, we demonstrated the presence of a coherent transversal barrier in the central channel of NPC, using high resolution transmission electron microscopy. It was found that the barrier is located in the middle of the central channel, i.e. at the level where the outer and inner nuclear membranes fuse. The thickness of this layer is evidently different in various NPCs and usually varies between 20 and 30 nm and its diameter is approximately 40 nm. The cytoplasmic and nuclear surfaces of the barrier are roughly parallel and plane. Moreover we suggest that the barrier may not be interrupted by any channel(s), at least not with a diameter above 10 nm. Further various appearances of the central channel with different particles were observed, presumably cargos and karyopherins captured in transit. A different type of central channel barrier with lipid bilayer membrane-like appearance is also discussed.
authors.affiliation: Laboratory of Electron Microscopy, Cancer Research Institute, Vlárska 7, 83391 Bratislava, Slovakia. jarmil.prachar@savba.sk
authors.forename: Jarmil
authors.initials: J
authors.lastname: Prachař
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002843:Chromatin / Q000648:ultrastructure; D006801:Humans; D007473:Ion Channels / Q000648:ultrastructure; D008051:Lipid Bilayers / Q000378:metabolism; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008867:Microtomy / Q000379:methods; D022022:Nuclear Pore / Q000648:ultrastructure*; D010743:Phospholipids / Q000378:metabolism
chemical_list: D002843:Chromatin; D007473:Ion Channels; D008051:Lipid Bilayers; D010743:Phospholipids