Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates. they consist of protein subunits denoted connexins (Cxs) which are encoded by a gene family. According to their Cx composition. https://www.spidertattooz.com/Kaiser-Copy-Stand-RS-1-with-RA-1-Arm-40-Counterbalanced-Column-and-18-x-20-Baseboard/