Extended Data Fig. 3: Identification of the minimal functional peptide sequence in the SMAD4 extension.
a, Schematic representation of WT and mutant SMAD4 with the terminal glycine residue (G592) indicated. b, SMAD4 protein expression determined by western blot after transfection of BxPC3 cells with WT SMAD4, T1657C mutant or T1657C with C-terminal Gly592Ala (G>A) / Gly592Val (G>V) mutations. c, Schematic representation of the SMAD4 extension amino acid sequence. The extension of 39 aa after the mutated stop codon was divided into four parts: A, B, C (10 aa each) & D (9 aa). These are indicated and this nomenclature is followed in the figure panels including main Fig. 4d. Further deletions of residues are indicated by subscripts showing the retained amino acid segments in the respective domains. d-i, SMAD4 protein expression determined by western blot (d,f,h) and quantified for replicates (e,g,i) in lysates from BxPC3 cells transfected with pEF-DEST51 empty vector (EV), WT SMAD4, SMAD4 with the full length extension (ABCD) or vectors expressing indicated truncations and deletions in the extension. All panels: n=3 biologically independent experiments, mean ± SEM, ANOVA with ***p<0.001, **p<0.01, *p<0.05. Numerical source data and unprocessed blots are provided with the paper.
