Trafficking of the plant potassium inward rectifier KAT1 in guard cell protoplasts of Vicia faba.
Trafficking of K+ inward (Kin+) rectifying channels was analyzed in guard cells of Vicia faba transfected with the Kin+ rectifier from Arabidopsis thaliana KAT1 fused to the green fluorescent protein (GFP). Confocal images and whole-cell patch-clamp measurements confirmed the incorporation of active KAT1 channels into the plasma membrane of transfected guard cell protoplasts. The Kin+ rectifier current density of the plasma membrane was much larger in transfected protoplasts than in wild-type (wt) protoplasts. This shows a coupling between K+ channel synthesis and incorporation of the channel into the plasma membrane. Pressure-driven increase and decrease in surface area led to the incorporation and removal of vesicular membrane carrying active Kin+ rectifier in wt and transfected protoplasts. These vesicular membranes revealed a higher channel density than the plasma membrane, suggesting that Kin+ rectifier remains in clusters during trafficking to and from the plasma membrane. The observed results can be explained by a model illustrating that vesicles of a pre-plasma membrane pool carry K+ channels preferentially in clusters during constitutive and pressure-driven exo- and endocytosis.
Hurst
Annette C
AC
Institute of Botany, Technical University of Darmstadt, 64287 Darmstadt, Germany.
Meckel
Tobias
T
Tayefeh
Sascha
S
Thiel
Gerhard
G
Homann
Ulrike
U
D029681:Arabidopsis Proteins; D001483:Base Sequence; D017931:DNA Primers; D018613:Microscopy, Confocal; D010940:Plant Proteins; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D031307:Vicia faba / Q000378:metabolism* / Q000648:ultrastructure
D029681:Arabidopsis Proteins; D017931:DNA Primers; C501210:KAT1 protein, Arabidopsis; D010940:Plant Proteins; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011993:Recombinant Fusion Proteins