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. 1999 Jan 19;96(2):319-21.
doi: 10.1073/pnas.96.2.319.

Plugging the leaks

D A Goodenough  1
Affiliations

Plugging the leaks

D A Goodenough. Proc Natl Acad Sci U S A. .
No abstract available

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Figures

Figure 1
Figure 1
A diagram of six epithelial cells packed into a portion of an epithelium. The apical and basolateral membranes are separated by tight junctions (shown as continuous red rings joining the cells). Selective epithelial permeability involves both the transcellular and paracellular routes. In the former, solutes are transported across the apical plasma membrane, diffuse through the cytoplasm (dashed arrow), and are then retransported out of the cell into the extracellular space beneath the tight junctions. In the paracellular route, solutes move through channels in the tight junction itself (solid arrow) and gain access to the paracellular spaces without entering the cytoplasm of the cells. The small box indicates the plane of section shown in diagram in Fig. 3.
Figure 2
Figure 2
Electron microscopy of tight junctions in liver from mouse bile canaliculi. (A) Freeze-fracture image of the canaliculus angles across the field of view from lower left to upper right. The tight junctions appear as branching and anastomosing strands on the P fracture face (above the canaliculus) and complementary grooves on the E fracture face (below the canaliculus). (B) Thin-section image in which the tight junctions can be seen flanking the microvillus-filled canaliculus. Horseradish peroxidase was introduced into the extracellular spaces via the vascular system and is seen to penetrate the extracellular spaces but is denied access to the canalicular lumen by the tight junctions. (Bar = 1 μm.)
Figure 3
Figure 3
A diagram of the vertical section (small box) in Fig. 1. The apical and basolateral membranes are separated by one or more membrane–membrane interactions extending in the plane normal to the figure to form the paracellular seal. In three dimensions, these interactions would anastomose in this plane and then branch, creating the weblike strand network seen in freeze-fracture images in Fig. 2. Two interactions are drawn here: apical, showing a fanciful bonding between two claudin proteins via their extracellular loops, and basal, showing a similar bonding between two occludin proteins, whose longer cytoplasmic C termini interact with the guanylate kinase domain of either ZO-1 or ZO-3. Actin is known to interact with the proline-rich tail of ZO-1. Each ZO-1 is shown interacting with ZO-2 via their second PDZ domains. The claudins and occludins are drawn as monomers; presumably they are oligomerized with themselves or with each other in the membrane. ∗ is placed in a chamber created between two membrane–membrane interactions, which may be isolated from both the apical and basolateral compartments.
See this image and copyright information in PMC

Comment on

References

    1. Boulpaep E L, Seely J F. Am J Physiol. 1971;221:1084–1096. - PubMed
    1. Goodenough D A, Revel J P. J Cell Biol. 1971;50:81–91. - PMC - PubMed
    1. Frömter E, Diamond J M. Nature (London) 1972;235:9–13. - PubMed
    1. Pappenheimer J R. J Membr Biol. 1987;100:137–148. - PubMed
    1. Madara J L, Pappenheimer J R. J Membr Biol. 1987;100:149–164. - PubMed

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