Figure 3. Connexin oligomerization pathways.

Connexins are co-translationally inserted into the ER membrane. Depending on the connexin subtype, oligomerization can occur either in the ERGIC (W type, Cx32, white) or the TGN (R type, Cx43, shaded). The potential for connexin oligomerization in the ER, driven by high levels of connexin expression, is also shown for Cx32. Hemichannels are subsequently transported to the plasma membrane, where they can function as channels or pair with hemichannels on adjacent cells to form complete intercellular channels. Channels at the plasma membrane further assemble into semi-crystalline arrays known as gap junction plaques, which can contain from tens to thousands of channels. Homogenous plaques are composed of either a single connexin or heteromeric connexins (not shown). Heterogeneous plaques contain regions enriched for different connexins. Adapted from [2], with permission.