Connexon

Connexon

Diagram of connexon and connexin structure

A connexon is a complex of six protein subunits called connexins that form a channel across the cell membrane. These channels are crucial components of gap junctions, which facilitate direct intercellular communication by allowing the passage of ions and small molecules between adjacent cells.

Structure

Connexons are hexameric assemblies of connexins, which are a family of structurally related transmembrane proteins. Each connexin subunit has four transmembrane domains, two extracellular loops, one intracellular loop, and cytoplasmic N- and C-termini. The connexins are arranged in a circular fashion to form a pore that spans the lipid bilayer of the cell membrane.

Function

Connexons play a critical role in maintaining homeostasis and enabling synchronized cellular activities. They allow the passage of ions, metabolites, and other small signaling molecules, which is essential for processes such as cardiac conduction, neuronal communication, and tissue homeostasis.

Assembly and Regulation

Connexons are assembled in the endoplasmic reticulum and Golgi apparatus before being transported to the cell membrane. The assembly and function of connexons are regulated by various factors, including phosphorylation, changes in pH, and calcium concentration. Connexons can dock with connexons from adjacent cells to form complete gap junction channels.

Clinical Significance

Mutations in connexin genes can lead to a variety of genetic disorders, such as Charcot-Marie-Tooth disease, nonsyndromic hearing loss, and certain types of skin disorders. Understanding the structure and function of connexons is crucial for developing therapeutic strategies for these conditions.

Related pages

• Gap junction
• Connexin
• Cell membrane
• Intercellular communication