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Mol Biol Cell

Title:		Organization of the yeast Golgi complex into at least four functionally distinct compartments
Author(s):		Brigance WT; Barlowe C; Graham TR;
Address:		"Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235, USA"
Journal Title:		Mol Biol Cell
Year:		2000
Volume:		11
Issue:		1
Page Number:		171 - 182
DOI:		10.1091/mbc.11.1.171
ISSN/ISBN:		1059-1524 (Print) 1059-1524 (Linking)
Abstract:		"Pro-alpha-factor (pro-alphaf) is posttranslationally modified in the yeast Golgi complex by the addition of alpha1,6-, alpha1,2-, and alpha1,3-linked mannose to N-linked oligosaccharides and by a Kex2p-initiated proteolytic processing event. Previous work has indicated that the alpha1,6- and alpha1,3-mannosylation and Kex2p-dependent processing of pro-alphaf are initiated in three distinct compartments of the Golgi complex. Here, we present evidence that alpha1,2-mannosylation of pro-alphaf is also initiated in a distinct Golgi compartment. Linkage-specific antisera and an endo-alpha1,6-D-mannanase (endoM) were used to quantitate the amount of each pro-alphaf intermediate during transport through the Golgi complex. We found that alpha1,6-, alpha1,2-, and alpha1,3-mannose were sequentially added to pro-alphaf in a temporally ordered manner, and that the intercompartmental transport factor Sec18p/N-ethylmaleimide-sensitive factor was required for each step. The Sec18p dependence implies that a transport event was required between each modification event. In addition, most of the Golgi-modified pro-alphaf that accumulated in brefeldin A-treated cells received only alpha1,6-mannosylation as did approximately 50% of pro-alphaf transported to the Golgi in vitro. This further supports the presence of an early Golgi compartment that houses an alpha1,6-mannosyltransferase but lacks alpha1,2-mannosyltransferase activity in vivo. We propose that the alpha1,6-, alpha1,2-, and alpha1,3-mannosylation and Kex2p-dependent processing events mark the cis, medial, trans, and trans-Golgi network of the yeast Golgi complex, respectively"
Keywords:		*Adenosine Triphosphatases Brefeldin A/pharmacology Endonucleases/metabolism Endoplasmic Reticulum/metabolism Exocytosis/physiology Fungal Proteins/*metabolism Glycosylation Golgi Apparatus/*metabolism Mannose/metabolism Mannosyltransferases/metabolism Ma;
Notes:		"MedlineBrigance, W T Barlowe, C Graham, T R eng GM-50409/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. 2000/01/19 Mol Biol Cell. 2000 Jan; 11(1):171-82. doi: 10.1091/mbc.11.1.171"