Family 1.B.28 - The Plastid Outer Envelope Porin of 24kDa Family       

Family ID: 53373

OEP24 is a high conductance, homooligomeric porin in the outer envelopes of pea chloroplasts, etioplasts and non-green root plastids. It forms a voltage-dependent, high conductance, slightly cationic-selective ion channel in reconstituted proteoliposomes. OEP24 transports triosephosphates, dicarboxylates, positively and negatively charged amino acids, sugars, ATP, and inorganic phosphate and thus exhibits low solute specificity. Structural predictions suggest the presence of seven amphipathic b-strands in a b-barrel arrangement. It contains 213 aas and shows a single homologue in Arabidopsis thaliana (At1g45170 212 aas; 60% identity). OEP24 can functionally replace mitochondrial VDAC (MPP family; TC #1.B.28) when the OEP24 gene is expressed in Saccharomyces cerevisiae. Thus, in yeast, it is targeted to the outer mitochondrial membrane, inserts properly, and functionally replaces VDAC. Nevertheless, it shows no sequence similarity to VDAC.