Fig. 7

Schematic representation of the pathways that lead to the internalization of entire gap junction plaques (I) and of central plaque portions (II), annular gap junction formation, fission, and degradation. Whether clathrin and clathrin-accessory proteins are involved in the internalization of small gap junction vesicles shown in (II) has not been determined, however is likely based on our EM analyses. Accrual of new channels (yellow line circumscribing the green gap junction plaque) is accompanied by the simultaneous internalization of central plaque portions consistent with previously published observations [63], [72]. Clathrin and accessory proteins are shown in patches in accordance to the appearance of clathrin on gap junction plaques [61], and the current thinking that clathrin may provide a scaffold for directed actin assembly, facilitating internalization of large structures such as gap junctions, viruses, and pathogenic bacteria [207], [208]. The manner in which clathrin and accessory proteins are drawn still remains somewhat speculative. NM = Connexin-free junctional membrane domain. (From ref. [73])