Voltage-dependent high-conductance channel with a slight cation-selectivity; selective for amino acids but excludes triosephosphates or uncharged sugars (By similarity). Non-essential amino acid-selective channel protein and translocation pore for NADPH:protochlorophyllide oxidoreductase A (PORA) and possibly PORB. Homodimer and oligomers in membrane. Detected in pollen and seeds. Present in leaves and cotyledons. Strongly expressed during the maturation phase in seeds and pollen grains, both desiccation-tolerant tissues. Regulated by ABI3 and ABI5. Belongs to the Tim17/Tim22/Tim23 family. Plastid outer envelope porin OEP16 (TC 1.B.30) subfamily.