1.B.34.3.1
Homooligomeric anion-selective outer envelope porin of 40 aas with a channel diameter of 1.4 nm, PorA (Abdali et al. 2013).  Positively charged residues in the channel lumen formed by the oligomeric α-helical wheels account for its anionic selectivity. Based on the sequence of PorA, a large functional transmembrane 40 aa peptide porin, built entirely from short synthetic α-helical peptides, has been construced (Krishnan R et al. 2019).