General Structure of the NPC

(Vasu and Forbes 2001)

Overall structure well conserved from yeast to mammals:

Yeast:

30 nucleoporins, 66 MDa

Vertebrates:

50-100 nucleoporins, 125 MDa

Structural Features:

-Central channel with maximum diameter of 26 nm

-8 fold symmetry

-Radial arms of spoke complex go through the pore membrane and project into the lumen of the nuclear envelope

-Cytoplasmic coaxial ring anchors and supports cytoplasmic filaments

Includes star ring covered by a thin ring

Supports 8 cytoplasmic filaments

Joined to entrance of transporter by 8 internal filaments

-Nucleplasmic coaxial ring supports and anchors nuclear basket

Significance of the structure:  

In order for nuclear transport to occur, the molecules being transported must interact with the peripheral structures of the NPC. 

Once this initial interaction event occurs, the transport of substances through the pore is mediated by interactions between the nucleoporins and the cargo molecule.

(Allen et al. 2000) 

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