The Journal of Neuroscience, 2000, 20:RC78:1-5
RAPID COMMUNICATION
Involvement of the Proximal C Terminus of the AMPA
Receptor Subunit GluR1 in Dendritic Sorting
Francesca
Ruberti and
Carlos G.
Dotti
Cell Biology and Biophysics Programme, European Molecular Biology
Laboratory, 69112 Heidelberg, Germany
Studies on dendritic sorting of transmembrane proteins in
hippocampal neurons in culture have shown that these cells use similar mechanisms as epithelial cells to sort transmembrane proteins to the
basolateral membrane domain. However, information is still scarce with
regard to which amino acidic sequences are required for dendritic
sorting in neurons. The glutamate receptor 1 (GluR1) subunit of the
AMPA receptor is present on the dendritic compartment of hippocampal
neurons in culture. To identify the GluR1 sorting signal responsible
for dendritic targeting, we have expressed the wild-type GluR1, a
deletion mutant in the C-terminal cytoplasmic tail, and chimeric GluR1
proteins in hippocampal neurons using a calcium phosphate transfection
method. The recombinant full-length GluR1 is polarized to the dendritic
domain. Truncated GluR1 with a deletion of the C-terminal cytoplasmic
tail is still delivered to the somatodendritic domain. However a
chimeric protein made of the luminal and transmembrane domain of the
influenza virus hemagglutinin (HA) fused to the GluR1 C-terminal
cytoplasmic tail (HaemR1) is detected in the somatodendritic domain.
This finding indicates that the GluR1 C-terminal cytoplasmic tail
contains a dendritic sorting signal, which redirects the axonal or
axonal-dendritic protein HA to the dendritic compartment exclusively.
Deletion analysis of HaemR1 shows that the proximal segment of the
GluR1 C-terminal cytoplasmic tail contains a novel dendritic sorting signal.
Key words:
dendrites; sorting; hippocampal neurons; GluR1; axonal; hemagglutinin
Copyright © 2000 Society for Neuroscience 0270-6474/00/$05.00/0