« Previous AbstractSynthesis and Characterization of Low-Cost Cresol-Based Benzoxazine Resins as Potential Binders in Abrasive Composites    Next AbstractPhyllosphere Fungal Communities of Plum and Antifungal Activity of Indigenous Phenazine-Producing Pseudomonas synxantha Against Monilinia laxa »

Yeast

Title:		Selective retention of secretory proteins in the yeast endoplasmic reticulum by treatment of cells with a reducing agent
Author(s):		Jamsa E; Simonen M; Makarow M;
Address:		"Institute of Biotechnology, University of Helsinki, Finland"
Journal Title:		Yeast
Year:		1994
Volume:		10
Issue:		3
Page Number:		355 - 370
DOI:		10.1002/yea.320100308
ISSN/ISBN:		0749-503X (Print) 0749-503X (Linking)
Abstract:		"We have used four glycoproteins as markers to study how disulfide bond formation and protein folding effect the intracellular transport of proteins in yeast. Under normal conditions, the vacuolar enzyme carboxypeptidase Y (CPY) and the secretory stress-protein hsp150 acquired disulfide bonds in the endoplasmic reticulum (ER). Treatment of living cells with the reducing agent dithiothreitol (DTT) prevented disulfide formation of newly synthesized CPY and hsp150, resulting in retention of the proteins in the ER. When DTT was removed, the sulfhydryls were reoxidized, and the transport of the proteins to their correct destinations was resumed. Even mature CPY, located in the vacuole, could be reduced with DTT, and reoxidized after removal of the drug. DTT treatment blocked intracellular transport of hsp150 only when present during the synthesis and translocation of the protein. Reduction of folded hsp150, accumulated in the ER due to a sec block prior to DTT treatment, did not inhibit its secretion. The Kar2p/BiP protein, a component of the ER lumen, was found to be associated with fully translocated reduced hsp150, but not with native hsp150, suggesting that Kar2p/BiP may be involved in the putative retention mechanism. The cysteine-free pro-alpha-factor, and invertase which was shown to have free sulfhydryls, were secreted and modified similarly in the presence and absence of DTT, showing that the secretory pathway of yeast functioned under reducing conditions"
Keywords:		Biological Transport Carboxypeptidases/metabolism Cathepsin A Disulfides/*metabolism Dithiothreitol/pharmacology Endoplasmic Reticulum/*metabolism Fungal Proteins/*metabolism *Glycoproteins Glycoside Hydrolases/metabolism *HSP70 Heat-Shock Proteins Heat-S;
Notes:		"MedlineJamsa, E Simonen, M Makarow, M eng Comparative Study Research Support, Non-U.S. Gov't England 1994/03/01 Yeast. 1994 Mar; 10(3):355-70. doi: 10.1002/yea.320100308"