Voltage-dependent high-conductance channel with a slight cation-selectivity; selective for amino acids but excludes triosephosphates or uncharged sugars. Non-essential amino acid-selective channel protein and translocation pore for NADPH:protochlorophyllide oxidoreductase A (PORA) and possibly PORB. Homodimer and oligomers in membrane. Belongs to the Tim17/Tim22/Tim23 family. Plastid outer envelope porin OEP16 (TC 1.B.30) subfamily.