LEVEL OF EXPRESSION IN, XENOPUS OOCYTES AFFECTS SOME CHARACTERISTICS OF A PLANT INWARD-RECTIFYING VOLTAGE-GATED K+ CHANNEL

The plant K+ channel KAT1 shows some similarity to animal voltage-gate d channels of the Shaker superfamily. Contrary to these animal counter parts, this plant channel is inwardly rectifying, being gated upon hyp erpolarization. Different levels of expression of KAT1 in Xenopus oocy tes could be obtained by increasing the amount of injected cRNA. The r esulting KAT1 gating and sensitivity to external caesium were signific antly changed. Similar findings have been published regarding animal v oltage-gated channels. The present data show that plant channels may a lso undergo modification of their activity upon modification of their level of expression.