« Previous AbstractThe Venus flytrap of periplasmic binding proteins: an ancient protein module present in multiple drug receptors    Next Abstract"Physico-Chemical, Nutritional, and Sensory Evaluation of Two New Commercial Tomato Hybrids and Their Parental Lines" »

J Biol Chem

Title:		Product of SEC53 is required for folding and glycosylation of secretory proteins in the lumen of the yeast endoplasmic reticulum
Author(s):		Feldman RI; Bernstein M; Schekman R;
Address:
Journal Title:		J Biol Chem
Year:		1987
Volume:		262
Issue:		19
Page Number:		9332 - 9339
DOI:
ISSN/ISBN:		0021-9258 (Print) 0021-9258 (Linking)
Abstract:		"Yeast secretory mutant sec53 cells accumulate inactive secretory glycoprotein precursors that remain associated with the endoplasmic reticulum (ER) at the restrictive temperature (37 degrees C). The possibility that precursor polypeptides fail to penetrate completely into the ER lumen was tested by examining the protease accessibility of accumulated invertase, mating pheromone precursor prepro-alpha-factor and the vacuolar protein precursor procarboxypeptidase Y in cell lysates. In all three cases, the secretory protein precursors are protected from the action of exogenous protease unless the membrane is permeabilized by including Triton X-100 or saponin in the incubation. These results suggest that the sec53 defect allows complete polypeptide translocation. Consistent with this interpretation, the precursor of invertase accumulates in a signal peptide-processed form. In addition, invertase and prepro-alpha-factor precursors contain a small amount of possibly aberrant carbohydrate. In mutant cells or in wild type cells treated with tunicamycin, a 10-kDa fragment of the N terminus of mature invertase assumes a conformation that is resistant to trypsin with or without detergent. This domain may be associated with an ER protein or may simply assume an unusual conformation as a consequence of deficient glycosyl modification"
Keywords:		Carboxypeptidases/metabolism Cathepsin A Cell Membrane Permeability Concanavalin A/pharmacology Endoplasmic Reticulum/*metabolism Glycoside Hydrolases/metabolism Glycosylation Mutation Protein Sorting Signals/metabolism Proteins/*metabolism Saccharomyces;
Notes:		"MedlineFeldman, R I Bernstein, M Schekman, R eng GM26755/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S. 1987/07/05 J Biol Chem. 1987 Jul 5; 262(19):9332-9"