As shown in the drawings in Figure 15–3, the lipid bilayer of the inner and outer nuclear membranes forms a continuous sheet, joined around the nuclear pores. As membranes are two-dimensional fluids, this would imply that membrane proteins can diffuse freely between the two nuclear membranes. Yet each of these two nuclear membranes has a different protein composition, reflecting different functions. How could you reconcile this apparent contradiction?

Figure 15–3

Transcribed Image Text:

DNA- membrane- bound ribosomes plasma membrane anaerobic archaeon inner nuclear membrane outer nuclear membrane C anaerobic eukaryotic cell nuclear pore nucleus endoplasmic reticulum cytosol