TY  - JOUR
A1  - Maitrejean, Marie
A1  - Wudick, Michael M.
A1  - Völker, Camilla
A1  - Prinsi, Bhakti
A1  - Müller-Röber, Bernd
A1  - Czempinski, Katrin
A1  - Pedrazzini, Emanuela
A1  - Vitale, Alessandro
T1  - Assembly and sorting of the tonoplast potassium channel AtTPK1 and its turnover by internalization into the Vacuole
JF  - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants
N2  - The assembly, sorting signals, and turnover of the tonoplast potassium channel AtTPK1 of Arabidopsis (Arabidopsis thaliana) were studied. We used transgenic Arabidopsis expressing a TPK1-green fluorescent protein (GFP) fusion or protoplasts transiently transformed with chimeric constructs based on domain exchange between TPK1 and TPK4, the only TPK family member not located at the tonoplast. The results show that TPK1-GFP is a dimer and that the newly synthesized polypeptides transiently interact with a thus-far unidentified 20-kD polypeptide. A subset of the TPK1-TPK4 chimeras were unable to assemble correctly and these remained located in the endoplasmic reticulum where they interacted with the binding protein chaperone. Therefore, TPK1 must assemble correctly to pass endoplasmic reticulum quality control. Substitution of the cytosolic C terminus of TPK4 with the corresponding domain of TPK1 was sufficient to allow tonoplast delivery, indicating that this domain contains tonoplast sorting information. Pulse-chase labeling indicated that TPK1-GFP has a half-life of at least 24 h. Turnover of the fusion protein involves internalization into the vacuole where the GFP domain is released. This indicates a possible mechanism for the turnover of tonoplast proteins.
Y1  - 2011
U6  - https://doi.org/10.1104/pp.111.177816
SN  - 0032-0889
VL  - 156
IS  - 4
SP  - 1783
EP  - 1796
PB  - American Society of Plant Physiologists
CY  - Rockville
ER  -