gap junction

The TNTs protrude from one pericyte to contact the other, where they terminate in a structure called a gap junction.

The gap junction permits the exchange of small molecules and calcium ions, but prevents the passage of large objects such as organelles.

The dim cell “recovers” its fluorescence over time as dye molecules that are still shining brightly migrate through the gap junction channels from the cell on the right.

When one hemichannel encounters another in the membrane of a neighboring cell, the two can dock with one another, forming a channel that connects the interior of one cell to the interior of its neighbor; a collection of these docked channels constitutes a gap junction.

The animation shows the main events in gap junction assembly—from the synthesis of gap junction proteins, called connexins, to the opening of the channels, allowing ions and small molecules to pass.