Progressive quality control of secretory proteins in the early secretory compartment by ERp44.
J Cell Sci
; 127(Pt 19): 4260-9, 2014 Oct 01.
Article
em En
| MEDLINE
| ID: mdl-25097228
ABSTRACT
ERp44 is a pH-regulated chaperone of the secretory pathway. In the acidic milieu of the Golgi, its C-terminal tail changes conformation, simultaneously exposing the substrate-binding site for cargo capture and the RDEL motif for ER retrieval through interactions with cognate receptors. Protonation of cysteine 29 in the active site allows tail movements in vitro and in vivo. Here, we show that conserved histidine residues in the C-terminal tail also regulate ERp44 in vivo. Mutants lacking these histidine residues retain substrates more efficiently. Surprisingly, they are also O-glycosylated and partially secreted. Co-expression of client proteins prevents secretion of the histidine mutants, forcing tail opening and RDEL accessibility. Client-induced RDEL exposure allows retrieval of proteins from distinct stations along the secretory pathway, as indicated by the changes in O-glycosylation patterns upon overexpression of different partners. The ensuing gradients might help to optimize folding and assembly of different cargoes. Endogenous ERp44 is O-glycosylated and secreted by human primary endometrial cells, suggesting possible pathophysiological roles of these processes.
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Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Transporte
/
Chaperonas Moleculares
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Retículo Endoplasmático
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Proteínas de Membrana
Limite:
Humans
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article