|
|
|
|
|
|
|
||
Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229
The localization of proteins to late-Golgi
membranes (TGN) of Saccharomyces cerevisiae is conferred by targeting motifs containing aromatic residues
in the cytosolic domains of these proteins. These signals
could act by directing retrieval from a post-Golgi compartment or by preventing exit from the TGN. To investigate the mechanism of localization of yeast TGN
proteins, we used the heterologous protein A-ALP
(consisting of the cytosolic domain of dipeptidyl aminopeptidase A [DPAP A] fused to the transmembrane and luminal domains of the vacuolar protein alkaline
phosphatase [ALP]), which localizes to the yeast TGN.
Insertion of the aromatic residue-based TGN localization motif (FXFXD) of DPAP A into the cytosolic domain of ALP results in a protein that resides in the TGN. We demonstrate that the FXFXD motif confers
Golgi localization through retrieval from a post-Golgi
compartment by detecting a post-Golgi processed form
of this protein in the TGN. We present an assay that
uncouples retrieval-mediated Golgi localization from
static retention-based localization, allowing measurement of the rate at which proteins exit the yeast TGN.
We also demonstrate that the cytosolic domain of
DPAP A contains additional information, separate
from the retrieval motif, that slows exit from the TGN. We propose a model for DPAP A localization that involves two distinct mechanisms: one in which the
FXFXD motif directs retrieval from a post-Golgi compartment, and a second that slows the rate at which
DPAP A exits the TGN.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
