The K+ channel KZM1 mediates potassium uptake into the phloem and guard cells of the C4 grass Zea mays.

In search of K(+) channel genes expressed in the leaf of the C(4) plant Zea mays, we isolated the cDNA of KZM1 (for K(+) channel Zea mays 1). KZM1 showed highest similarity to the Arabidopsis K(+) channels KAT1 and KAT2, which are localized in guard cells and phloem. When expressed in Xenopus oocytes, KZM1 exhibited the characteristic features of an inward-rectifying, potassium-selective channel.