What role do connexins play in gap junctions?

Connexins are integral membrane proteins that assemble to form gap junctions, which are specialized intercellular channels that allow for direct communication between adjacent cells. The primary role of connexins in this context is to facilitate fast signal transmission.

When connexins form these gap junctions, they create pores that permit the passage of ions and small molecules between cells. This direct channeling of signals enables electrical and chemical communication, allowing cells to respond quickly to changes in their environment or to coordinate activities. The ability of adjacent cells to exchange ions and second messengers rapidly is critical in various physiological processes, such as cardiac muscle contraction and neuronal signaling.

The other options do not accurately represent the function of connexins. For instance, connexins do not form protective barriers, anchor cilia and flagella, or regulate cell growth directly. Their distinct role in facilitating intercellular communication through gap junctions is what sets them apart in cellular biology.