Unfolded proteins in the endoplasmic reticulum of Saccharomyces cerevi
siae trigger a specialized RNA splicing event that allows the subseque
nt translation of the Hac1p transcription factor. This splicing can be
reconstituted with Ire1p, a transmembrane kinase that has a site-spec
ific RNase activity, and tRNA ligase. (C) Current Biology Ltd.