Fig. 7. Co- and post-transitional insertion of wild-type and mutated connexins into microsomal membranes. WtCx32 and Cx26, Cx32I28L or Cx32V206I were synthesised in the absence of microsomal membranes (-), or with microsomes added co-translationally (co) or post-translationally (po). For co- and post-translational studies, membranes were separated from free connexins by centrifugation through a sucrose cushion, washed in an alkaline buffer and then analysed for the presence of membrane-inserted connexins by SDS-PAGE. Lanes 1-3, Cx26; lanes 4-6, Cx32; lanes 7-9, Cx32I28L; lanes 10-12, Cx32V206I. The faster migrating bands (approx. 5 kDa less than full length connexins) are caused by abnormal proteolytic cleavage occurring in vitro due to a signal peptidase (Falk et al., 1997).
