Fig. 4: Identification and bioinformatic analysis of putative β-signals in chloroplast β-barrel proteins.

a Outer envelope β-barrel proteins were assigned to four functional groups. Conservation analysis using ConSurf was performed on the predicted β-signal sequences, and a representative example is shown for each group. b AlphaFold 3 model of Oep80 interacting with the Oep21a β-1 peptide (residues 159–167). IPTM = 0.6. Conservation analysis of the β1 strand of Oep80 is also shown. Black dotted lines in the inset indicate backbone N-to-O distances of 3 Å or less, i.e., likely hydrogen bonding interactions. *Although conservation score is low for this residue, all 150 sampled orthologs have an aromatic side chain at this position (either Y or F).