514 publications from this institution
XBP1u, a central component of the unfolded protein response (UPR), is a mammalian protein containing a functionally critical translational arrest peptide (AP). Here, we present a 3 Å cryo-EM structure of the stalled human XBP1u AP. It forms a unique turn in the upper part of the ribosomal exit tunnel and causes a subtle distortion of the peptidyl transferase center, explaining the temporary translational arrest induced by XBP1u. During ribosomal pausing the hydrophobic region 2 (HR2) of XBP1u is recognized by SRP, but fails to efficiently gate the Sec61 translocon. An exhaustive mutagenesis scan of the XBP1u AP revealed that only 10 out of 21 mutagenized positions in the XBP1u AP are optimal with respect to translational arrest activity. Thus, XBP1u has evolved to induce an intermediate level of translational arrest, allowing efficient targeting by SRP without activating the Sec61 channel and thereby serving its central function in the UPR.
No abstract is provided for this article.
This folder contains the raw data that was used for quantifications (and the quantifications in an Excel sheet). The raw data (.txt files called EasyQuant files) was extracted from autoradiographs of SDS-PAGE gels using the ImageGauge software from Fuji (associated with the Fuji gel scanner). This machine has since been discontinued (these data were collected 2014-2016). The .txt files were imported into EasyQuant and fitted to a Gaussian distribution automatically by the software (software developed in the Gunnar von Heijne lab by Dr. Rickard Hedman), and the Ffl (fraction full length) was calculated.
