|
|
|
|
|
|
|
||
J. Cell Biol.,
Volume 143, Number 5, November 30, 1998 1183-1199
Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340
Plant cells may contain two functionally distinct vacuolar compartments. Membranes of protein
storage vacuoles (PSV) are marked by the presence of
-tonoplast intrinsic protein (TIP), whereas lytic vacuoles (LV) are marked by the presence of 
-TIP. Mechanisms for sorting integral membrane proteins to the different vacuoles have not been elucidated. Here we
study a chimeric integral membrane reporter protein
expressed in tobacco suspension culture protoplasts whose traffic was assessed biochemically by following
acquisition of complex Asn-linked glycan modifications
and proteolytic processing, and whose intracellular localization was determined with confocal immunofluorescence. We show that the transmembrane domain of
the plant vacuolar sorting receptor BP-80 directs the reporter protein via the Golgi to the LV prevacuolar
compartment, and attaching the cytoplasmic tail (CT)
of -TIP did not alter this traffic. In contrast, the -TIP
CT prevented traffic of the reporter protein through
the Golgi and caused it to be localized in organelles separate from ER and from Golgi and LV prevacuolar
compartment markers. These organelles had a buoyant
density consistent with vacuoles, and -TIP protein
colocalized in them with the -TIP CT reporter
protein when the two were expressed together in protoplasts. These results are consistent with two separate
pathways to vacuoles for membrane proteins: a direct
ER to PSV pathway, and a separate pathway via the
Golgi to the LV.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
