NMR studies of HAC1 mRNA.

HAC1 is a transcription factor related to Unfolded Protein Response (UPR) signaling in yeast. Processing of HAC1 mRNA on Endoplasmic reticulum (ER) plays a key role in UPR signaling pathway, but the recognition mechanism of HAC1 mRNA by processing enzyme Ire1p is still unclear. Here, the solution structure of HAC1 mRNA was investigated by Nuclear Magnetic Resonance (NMR) spectroscopy, focusing on the structure of the recognition site of Ire1p in HAC1 mRNA. From the NOESY spectrum, imino proton signals of 5' processing regions of HAC1 mRNA were assigned and it was found that this region forms the stem-loop structure.