Chapter 5 │ Page 166 Figure 3: Representations of the 3D structure of Cx26 proteins-composed connexons. The Cx26 structure can be obtained from the Protein Data Bank website (https://www.rcsb.org/) (accession no. 2ZW3). Side view (on the left) and top view (on the right). (A) Each color represents a Cx monomer. (B) Homomeric connexon. (C) Heteromeric connexon. (D) Schematic representation of GJIC (or only GJ) between Cx46 proteinscomposed connexons (4 possibilities are shown). The Cx46 structure can be obtained from the Protein Data Bank website (https://www.rcsb.org/) (accession no. 6MHQ). Exchange of possible types of ions, amino acids, secondary messengers, cancer-associated signaling molecules, nutrients and microRNAs between two cells is illustrated as geometrical shapes of di erent colors. For simplicity only a few examples for each class are shown. It has already been reported that homotypic and heterotypic GJIC exhibit di erent electrical potentials between the inside and outside (Vi‒o) of the cells and di erent voltage di erences between the interiors of communicating cells, known as the trans-junctional voltage (Vj). For example, homotypic Cx26 proteins-composed GJs (Cx26-GJs) are sensitive to both Vi‒o and Vj, while homotypic Cx32 proteinscomposed GJs (Cx32-GJs) are sensitive to only Vi‒o [63]. Conversely, heterotypic
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