Figure 2
From: Molecular connections between nuclear and ciliary import processes
Model of the size-dependent diffusion barrier at the base of the cilium. The base of the cilium contains a size-dependent barrier to entry of soluble proteins. Molecules that are 10 kDa (purple) can enter both the cilium and nucleus but 70 kDa (red) molecules are restricted from both compartments. Insets shows fluorescence micrographs of the cilia of NIH3T3 cells co-expressing monomeric GFP (1x) or tandem (2x or 3x) GFPs together with Arl13b (red) to mark the ciliary compartment. Despite the difference in molecular weight, monomeric and tandem fluorescent protein constructs can enter the ciliary compartment, presumably due to their similar diameters. GFP, green fluorescent protein; NPC, nuclear pore complexes.