analysis-protein-folding-transport-degradation-living-cells

Analysis of Protein Folding, Transport, and Degradation in Living Cells by Radioactive Pulse Chase

Radioactive pulse-chase labeling is a powerful tool for studying the conformational maturation, the transport to their functional cellular location, and ...

Utrecht University

In this article, we will cover the folding of proteins in the lumen of the endoplasmic reticulum (ER), including the role of three types of covalent modifications: signal peptide removal, N-linked glycosylation, and disulfide bond formation, as well as the function and importance of resident ER folding factors. These folding factors consist of classical chaperones and their cochaperones, the carbohydrate-binding chaperones, and the folding catalysts of the PDI and proline cis-trans isomerase families. We will conclude with the perspective of the folding protein: a comparison of characteristics and folding and exit rates for proteins that travel through the ER as clients of the ER machinery.

Protein folding in the endoplasmic reticulum.

Folding of influenza virus hemagglutinin (HA) in the endoplasmic reticulum has been well defined in mammalian cells. In different mammalian cell lines the protein follows the same folding pathway with identical folding intermediates, but folds with very different kinetics. To examine the effect of cellular context on HA folding and to test to which extent insect cells would support the HA folding process, we expressed HA in Sf9 insect cells. Strikingly, in this invertebrate system HA folded faster and more efficiently, still via the same folding intermediates as in vertebrate cells. Our results suggest that insect cells provide a highly efficient and effective folding environment for influenza virus HA and the ideal production platform for HA (emergency) vaccines. 

Folding of influenza virus hemagglutinin in insect cells is fast and efficient.

Pharmacological intervention to treat the lethal genetic disease cystic fibrosis has become reality, even for the severe, most common folding mutant F508del CFTR. CFTR defects range from absence of the protein, misfolding that leads to degradation rather than cell-surface localization (such as F508del), to functional chloride-channel defects on the cell surface. Corrector and potentiator drugs improve cell-surface location and channel activity, respectively, and combination therapy of two correctors and a potentiator have shown synergy. Several combinations are in the drug-development pipeline and although the primary defect is not repaired, rescue levels are reaching those resembling a cure for CF. Combination therapy with correctors may also improve functional CFTR mutants and benefit patients on potentiator therapy.

Article	Year
Protein folding in the endoplasmic reticulum. Cold Spring Harbor perspectives in biology\| PubMed ID: 23637286	2013
Folding of influenza virus hemagglutinin in insect cells is fast and efficient. Journal of biotechnology\| PubMed ID: 25828453	2015
Correcting CFTR folding defects by small-molecule correctors to cure cystic fibrosis. Current opinion in pharmacology\| PubMed ID: 29055231	2017

Ineke Braakman

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