Fig. 3

The p.L13_L15del E-cadherin mutant is regulated by cellular post-translational mechanisms. a cDNA sequences of mutant plasmids inducing the deletion of one, two or three leucine residues. b Representative scheme of the cell-free system for in vitro protein translation. Constructs encoding the wild-type and the mutant CDH1 cDNAs were used as templates for the production of E-cadherin molecules. c Coupled transcription and translation of E-cadherin was detected by Western blotting. d Band intensity was quantified and normalized against wild-type plasmid. Intensity average + SE is represented in the graph. e Illustration of the cellular model: E-cadherin negative cells were transfected with plasmids encoding the wild-type and the sequential CDH1 mutants. f E-cadherin levels produced by cells transfected with the p.L15del, the p.L14_L15del and the p.L13_L15del mutants. α-Tubulin was used as a loading control. g Quantification of band intensity is showed in the graph. (h) Regulation mechanism of E-cadherin mutant p.L13_L15del. In a wild-type context, the binding of signal recognition particle (SRP) to the signal peptide sequence of the nascent polypeptide causes a temporary pause in translation. Subsequently, SRP-bound ribosome attaches to SRP receptor located at the membrane of the endoplasmic reticulum, enabling translation to continue and translocation to begin. SRP is released and SRP receptor is recycled. The newly synthesized protein undergoes folding and trafficking to its correct location at the plasma membrane. The presence of the p.L13_L15del mutation can, however, impair the binding of SRP and, consequently, induce an evident arrest of E-cadherin translation, which is associated with several deleterious cellular effects