| Comments |
"Nuclear pore complexes are proteinaceous structures embedded
in the double membrane of the nuclear envelope. In order
to understand how the NPC functions, it is useful to examine
the similarities and differences between NPCs from the yeast
Saccharomyces cerevisiae and the frog Xenopus laevis. The
NPC is a large structure with a molecular weight of approximately
125 MDa in vertebrates and 66 MDa in yeast [BNID 111129]. A
vertebrate cell nucleus contains on the order of 2,000 NPCs,
whereas the smaller yeast nucleus contains approximately
200. NPCs have eight-fold rotational symmetry through the
central axis of the pore and two-fold mirror symmetry
through the plane of the nuclear envelope, suggesting
assembly as a modular structure, a notion that is supported
by structural and biochemical analysis of pore complex
assembly in vitro [refs 3,4]." |