| Electrophysiological characterization ( macroscopic and single channel currents ) of AKT 2 in both Xenopus oocytes and COS cells revealed a unique gating mode and sensitivity to pH ( weak inward rectification , inhibition , and increased rectification upon internal or external acidification ) , suggesting that AKT 2 has enough functional plasticity to perform different functions in phloem tissue of source and sink organs . ^^^ |