Trafficking of the plant potassium inward rectifier KAT1 in guard cell protoplasts of Vicia faba

Plant J. 2004 Feb;37(3):391-7. doi: 10.1046/j.1365-313x.2003.01972.x.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis Proteins
  • Base Sequence
  • DNA Primers
  • Microscopy, Confocal
  • Plant Proteins
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Potassium Channels, Inwardly Rectifying*
  • Protein Transport
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Vicia faba / metabolism*
  • Vicia faba / ultrastructure

Substances

  • Arabidopsis Proteins
  • DNA Primers
  • KAT1 protein, Arabidopsis
  • Plant Proteins
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Recombinant Fusion Proteins