How many connexin proteins arrange themselves to form one connexon?

1. A gap junction develops from proteins sitting in the plasma membrane. 2. Those proteins are called connexins. 3. A set of six connexins arranges itself into an elongated configuration shaped like a donut. 4. That six-protein assembly is called a connexon. 5. When the pores of connexons in two adjacent cells align, a channel between the cells forms. 6. Nine is the count of microtubule doublets in a flagellum, not of connexins, so that answer borrows a number from elsewhere. 7. One connexon is built from six connexins. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 4 "Cell Structure", section 4.6 Connections between Cells and Cellular Activities_