A gap junction channel is built when six connexin proteins arrange into a structure called a:

1. Gap junctions link the cytoplasm of two neighbouring animal cells. 2. The channel is assembled from a repeating protein unit. 3. Gap junctions develop when a set of six proteins called connexins arrange themselves in an elongated donut-like configuration. 4. That configuration is called a connexon. 5. Desmosomes and hemidesmosomes are anchoring junctions and carry no such channel. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 4 'Cell Structure', sections 4.1-4.6_