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1.B.77  The Chloroplast Outer Membrane Porin (Oep23) Family

Oep23 is found in the entire plant lineage from green algae to flowering plants. It is expressed in all organs and developmental states tested so far. The reconstituted recombinant protein Oep23 from pea forms a high conductance ion channel with a maximal conductance in the fully open state of 466 ± 14pS at a holding potential of +100 mV (in 250 mM KCl) (Goetze et al. 2015). The Oep23 channel is cation-selective (PK+ : PCl- = 15 : 1) with a voltage-dependent open probability of maximal Vmem = 0 mV. Oep23 activity appears to be a single channel unit that does not assemble into a multiple pore complex like bacterial type porins or mitochondrial voltage dependent anion channels. Thus, Oep23s are ion channels in the outer envelope of chloroplasts involved in solute exchange (Goetze et al. 2015)

The generalized reaction catalyzed by Oep23 is:

solutes (out) ↔ soutes (in)

References associated with 1.B.77 family:

Goetze, T.A., M. Patil, I. Jeshen, B. Bölter, S. Grahl, and J. Soll. (2015). Oep23 forms an ion channel in the chloroplast outer envelope. BMC Plant Biol 15: 47. 25849634