title: Targeting of vacuolar membrane localized members of the TPK channel family.
abstract: Four members of the tandem-pore potassium channel family of Arabidopsis thaliana (TPK1, 2, 3, and 5) reside in the vacuolar membrane, whereas TPK4 is a plasma membrane K(+)-channel. By constructing chimeras between TPK1 and TPK4, we attempted to identify channel domains involved in the trafficking process and found that the TPK1 cytoplasmic C-terminal domain (CT) is critical for the ER- as well as Golgi-sorting steps. Following site-directed mutagenesis, we identified a diacidic motif (DLE) required for ER-export of TPK1. However, this diacidic motif in the C-terminus is not conserved among other members of the TPK family, and TPK3 sorting is independent of its CT. Moreover, the 14-3-3 binding site of TPK1, essential for channel activation, is not involved in channel sorting.
authors.affiliation: University of Würzburg, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Dunkel
authors.forename: Andreas
authors.initials: A
authors.lastname: Latz
authors.forename: Karin
authors.initials: K
authors.lastname: Schumacher
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller
authors.forename: Dirk
authors.initials: D
authors.lastname: Becker
authors.forename: Rainer
authors.initials: R
authors.lastname: Hedrich
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D001692:Biological Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D015221:Potassium Channels / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D021382:Protein Sorting Signals; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013347:Subcellular Fractions / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D029681:Arabidopsis Proteins; D015221:Potassium Channels; D021382:Protein Sorting Signals; D011994:Recombinant Proteins