Malectin participates in a backup glycoprotein quality control pathway in the mammalian ER

Galli, Carmela; Bernasconi, Riccardo; Soldà, Tatiana; Calanca, Verena; Molinari, Maurizio

doi:10.1371/journal.pone.0016304

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Journal article

Malectin participates in a backup glycoprotein quality control pathway in the mammalian ER

Galli, Carmela Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland
Bernasconi, Riccardo Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland
Soldà, Tatiana Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland
Calanca, Verena Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland
Molinari, Maurizio Institute for Research in Biomedicine (IRB), Faculty of Biomedical Sciences, Università della Svizzera italiana, Switzerland - School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

26.01.2011

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Plos one. - 2011, vol. 6, no. 1, p. e16304

English Malectin is a conserved, endoplasmic reticulum (ER)-resident lectin that recognizes high mannose oligosaccharides displaying terminal glucose residues. Here we show that Malectin is an ER stress-induced protein that selectively associates with glycopolypeptides without affecting their entry and their retention in the Calnexin chaperone system. Analysis of the obligate Calnexin client influenza virus hemagglutinin (HA) revealed that Calnexin and Malectin associated with different timing to different HA conformers and that Malectin associated withmisfolded HA. Analysis of the facultative Calnexin clients NHK and a1-antitrypsin (a1AT) revealed that induction of Malectin expression to simulate conditions of ER stress resulted in persistent association between the ER lectin and themodel cargo glycoproteins, interfered with processing of cargo- linked oligosaccharides and reduced cargo secretion. We propose that Malectin intervention is activated upon ER stress to inhibit secretion of defective gene products that might be generated under conditions of aberrant functioning of the ER quality control machinery.

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