Reference "Rice SCAMP1 Defines Clathrin-Coated, trans-Golgi-Located Tubular-Vesicular Structures as an Early Endosome in Tobacco BY-2 Cells"

Reference ID

11449

Title

Rice SCAMP1 Defines Clathrin-Coated, trans-Golgi-Located Tubular-Vesicular Structures as an Early Endosome in Tobacco BY-2 Cells

Source

The Plant cell, 2007, vol. , pp. -

Authors (7)

Lam-S-K	Siu-C-L
Hillmer-S	Jang-S
An-G	Robinson-D-G
Jiang-L

Abstract

We recently identified multivesicular bodies (MVBs) as prevacuolar compartments
(PVCs) in the secretory and endocytic pathways to the lytic vacuole in tobacco
(Nicotiana tabacum) BY-2 cells. Secretory carrier membrane proteins (SCAMPs) are
post-Golgi, integral membrane proteins mediating endocytosis in animal cells. To
define the endocytic pathway in plants, we cloned the rice (Oryza sativa)
homolog of animal SCAMP1 and generated transgenic tobacco BY-2 cells expressing
yellow fluorescent protein (YFP)-SCAMP1 or SCAMP1-YFP fusions. Confocal
immunofluorescence and immunogold electron microscopy studies demonstrated that
YFP-SCAMP1 fusions and native SCAMP1 localize to the plasma membrane and mobile
structures in the cytoplasm of transgenic BY-2 cells. Drug treatments and
confocal immunofluorescence studies demonstrated that the punctate cytosolic
organelles labeled by YFP-SCAMP1 or SCAMP1 were distinct from the Golgi
apparatus and PVCs. SCAMP1-labeled organelles may represent an early endosome
because the internalized endocytic markers FM4-64 and AM4-64 reached these
organelles before PVCs. In addition, wortmannin caused the redistribution of
SCAMP1 from the early endosomes to PVCs, probably as a result of fusions between
the two compartments. Immunogold electron microscopy with high-pressure frozen/freeze-
substituted samples identified the SCAMP1-positive organelles as tubular-
vesicular structures at the trans-Golgi with clathrin coats. These early
endosomal compartments resemble the previously described partially coated
reticulum and trans-Golgi network in plant cells.