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The internal environment of the eukaryotic cell is divided by membranes into various organelles, containing diverse functional subcompartments, which allow complex cellular life. The quality control of newly made secretory proteins relies on the ability of the endoplasmic reticulum (ER) to segregate and compartmentalize molecules at different folding(More)
In order to maintain proper cellular functions, all living cells, from bacteria to mammalian cells, must carry out a rigorous quality control process in which nascent and newly synthesized proteins are examined. An important role of this process is to protect cells against pathological accumulation of unfolded and misfolded proteins. The endoplasmic(More)
Endoplasmic reticulum α1,2 mannosidase I (ERManI), a central component of ER quality control and ER-associated degradation (ERAD), acts as a timer enzyme, modifying N-linked sugar chains of glycoproteins with time. This process halts glycoprotein folding attempts when necessary and targets terminally misfolded glycoproteins to ERAD. Despite the importance(More)
A hallmark of Huntington's disease is the pronounced sensitivity of striatal neurons to polyglutamine-expanded huntingtin expression. Here we show that cultured striatal cells and murine brain striatum have remarkably low levels of phosphorylation of translation initiation factor eIF2α, a stress-induced process that interferes with general protein synthesis(More)
AIM To investigate the existence and levels of sH2a, a soluble secreted form of the asialoglycoprotein receptor in human serum. METHODS Production of recombinant sH2a and development of a monoclonal antibody and an enzyme-linked immunosorbent assay (ELISA). This assay was used to determine the presence and concentration of sH2a in human sera of(More)
Endoplasmic reticulum-associated degradation (ERAD) of a misfolded glycoprotein in mammalian cells requires the removal of 3-4 alpha 1,2 linked mannose residues from its N-glycans. The trimming and recognition processes are ascribed to ER Mannosidase I, the ER-degradation enhancing mannosidase-like proteins (EDEMs), and the lectins OS-9 and XTP3-B, all(More)
We found that a localization artifact can arise from common immunofluorescence methods. Specifically, cell fixation and permeabilization can cause mislocalization of a type II membrane-bound protein, ER mannosidase I, from its native localization in vesicles to the Golgi complex. Live cell microscopy and interestingly also mild cell fixation with(More)
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