Connexin 40 is a protein that forms gap junctions, which are channels that allow communication between adjacent cells. It is primarily found in the heart and blood vessels, playing a crucial role in maintaining proper electrical signaling and coordination of heartbeats. This protein is part of the connexin family, which includes other members like Connexin 43 and Connexin 26. Mutations or dysfunctions in Connexin 40 can lead to various cardiovascular issues, highlighting its importance in heart health and overall circulatory system function.