Connexins follow the classical secretory transport route from the ER to the plasma membrane: ER -> ERGIC -> Golgi -> TGN (Trans Golgi Network) -> PM (Plasma Membrane). All connexins assemble or oligomerize into hexameric connexons. The site of assembly varies and depends on Cx isoform, or cell type (see Koval et al., 2006).
Oligomerization of connexins has been observed during ER membrane insertion (Cx32), just after exit from the ER, in the ER-Golgi-intermediate compartment (Cx26) and inside the Trans-Golgi Network (Cx43) (Falk et al. 1997; Ahmad et al. 1999; Musil and Goodenough 1993; Diez et al. 1999).