Association of plant K+(in) channels is mediated by conserved C-termini and does not affect subunit assembly.
Inward rectifying potassium (K+(in)) channels play an important role in turgor regulation and ion uptake in higher plants. Here, we report a previously unrecognized feature of these proteins: K+(in) channel C-terminal polypeptides mediate channel protein interactions. Using a C-terminal fragment of potato guard cell K+(in) channel KST1 in a yeast two-hybrid screen two novel putative K+(in) channel proteins (SKT2 and SKT3) were identified by interaction of their C-termini which contained a conserved domain (K(HA)). Interactions were confirmed by Western blot-related assays utilizing K+(in) channel C-termini fused to green fluorescence protein. Although deletion of the K(HA)-domain abolished these interactions, K+(in) currents were still detectable by patch-clamp measurements of insect cells expressing these KST1 mutants, indicating that formation of a functional channel does not depend on this C-terminal domain.
Ehrhardt
T
T
Max-Planck-Institut für Molekulare Pflanzenphysiologie (MPI-MOPP), Potsdam, Germany.
Zimmermann
S
S
Müller-Röber
B
B
D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D015221:Potassium Channels / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011198:Solanum tuberosum; D018411:Spodoptera / Q000166:cytology / Q000502:physiology
D010940:Plant Proteins; D015221:Potassium Channels