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J Cell Biol. 2010 Aug 23;190(4):637-50. doi: 10.1083/jcb.200908092. Epub 2010 Aug 16.

BAG-6 is essential for selective elimination of defective proteasomal substrates.

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  • 1Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan.

Abstract

BAG-6/Scythe/BAT3 is a ubiquitin-like protein that was originally reported to be the product of a novel gene located within the human major histocompatibility complex, although the mechanisms of its function remain largely obscure. Here, we demonstrate the involvement of BAG-6 in the degradation of a CL1 model defective protein substrate in mammalian cells. We show that BAG-6 is essential for not only model substrate degradation but also the ubiquitin-mediated metabolism of newly synthesized defective polypeptides. Furthermore, our in vivo and in vitro analysis shows that BAG-6 interacts physically with puromycin-labeled nascent chain polypeptides and regulates their proteasome-mediated degradation. Finally, we show that knockdown of BAG-6 results in the suppressed presentation of MHC class I on the cell surface, a procedure known to be affected by the efficiency of metabolism of defective ribosomal products. Therefore, we propose that BAG-6 is necessary for ubiquitin-mediated degradation of newly synthesized defective polypeptides.

PMID:
20713601
[PubMed - indexed for MEDLINE]
PMCID:
PMC2928017
Free PMC Article
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