Aberrant substrate engagement of the ER translocon triggers degradation by the Hrd1 ubiquitin ligase.
J Cell Biol
; 197(6): 761-73, 2012 Jun 11.
Article
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| MEDLINE
| ID: mdl-22689655
ABSTRACT
Little is known about quality control of proteins that aberrantly or persistently engage the endoplasmic reticulum (ER)-localized translocon en route to membrane localization or the secretory pathway. Hrd1 and Doa10, the primary ubiquitin ligases that function in ER-associated degradation (ERAD) in yeast, target distinct subsets of misfolded or otherwise abnormal proteins based primarily on degradation signal (degron) location. We report the surprising observation that fusing Deg1, a cytoplasmic degron normally recognized by Doa10, to the Sec62 membrane protein rendered the protein a Hrd1 substrate. Hrd1-dependent degradation occurred when Deg1-Sec62 aberrantly engaged the Sec61 translocon channel and underwent topological rearrangement. Mutations that prevent translocon engagement caused a reversion to Doa10-dependent degradation. Similarly, a variant of apolipoprotein B, a protein known to be cotranslocationally targeted for proteasomal degradation, was also a Hrd1 substrate. Hrd1 therefore likely plays a general role in targeting proteins that persistently associate with and potentially obstruct the translocon.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Saccharomyces cerevisiae
/
Ubiquitina-Proteína Ligasas
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Retículo Endoplásmico
Idioma:
En
Revista:
J Cell Biol
Año:
2012
Tipo del documento:
Article
País de afiliación:
Estados Unidos