Connexine

Connexins are a family of transmembrane proteins that assemble to form gap junctions. Gap junctions are specialized protein channels that directly connect the cytoplasm of adjacent cells, allowing for the passage of small molecules and ions. This intercellular communication is crucial for a wide range of physiological processes, including cell-to-cell signaling, electrical coupling in excitable tissues like the heart and brain, and the coordinated growth and development of tissues.

There are numerous connexin genes identified in mammals, and the specific connexin subtypes expressed in a cell determine the properties of the gap junction, including its size selectivity and gating characteristics. For example, connexin 43 (Cx43) is abundant in the heart and is essential for maintaining coordinated cardiac contraction. Mutations in connexin genes can lead to various diseases, underscoring their vital role in cellular function. These diseases are often referred to as connexinopathies and can affect the skin, nervous system, heart, and other organs. The study of connexins and gap junctions provides important insights into cellular communication and disease pathogenesis.