Unfolded Proteins

Stitching mRNA back together again

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Science  15 Aug 2014:
Vol. 345, Issue 6198, pp. 783
DOI: 10.1126/science.345.6198.783-a

RtcB (red) co-localizes with the endoplasmic reticulum (green)

PHOTO: LU ET AL., MOLECULAR CELL (31 JULY 2014) © 2014 ELSEVIER INC.

Cells get rid of toxic, inappropriately folded proteins in a process called the unfolded protein response (UPR). The UPR occurs in the cell's endoplasmic reticulum, which folds and sorts proteins. It requires an unconventional type of RNA splicing: the removal of small pieces of genetic material called introns from messenger RNA (mRNA). But biologists weren't sure how the spliced mRNA got put back together. Lu et al. now report that the enzyme RtcB patches together the two halves of a spliced mRNA that codes for XBP1, an important regulator of the UPR. In the endoplasmic reticulum, RtcB bound another enzyme, IREα, which splices the intron out of the XBP1 mRNA.

Mol. Cell 55, 10.1016/j.molcel.2014.06.032 (2014).

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