Less is pore

After proteomic analysis identified 29 different nucleoporins in the yeast nuclear pore complex (NPC), it looked as if the significantly larger and heavier mammalian NPC might contain twice that number of distinct proteins. On page 915, Cronshaw et al. now describe a proteomic analysis of mammalian NPCs that arrives at a surprising tally of mammalian nucleoporins: 29. Despite the numerical similarity, the new work identifies important differences between the two systems and establishes a basis for comparison.

The authors obtained a highly purified NPC fraction from rat liver, and then used mass spectrometry to identify and characterize the proteins making up the NPC. Although the NPCs appear to have remained intact through the purification, only 29 nucleoporins were identified in the final preparation. Two-thirds of the nucleoporins are conserved between yeast and mammalian NPCs,...