Figure 1: Emergency response at the endoplasmic reticulum. | Nature

Figure 1: Emergency response at the endoplasmic reticulum.

From: How to combat stress

Figure 1

a, In the unstressed cell, protein folding within the endoplasmic reticulum occurs efficiently; the unfolded protein sensor and signalling protein Ire1p is inactive, and the HAC1 messenger RNA remains untranslated in the cytoplasm. b, Under stress, protein folding is disrupted and unfolded proteins accumulate in the endoplasmic reticulum. It emerges3,4 that the binding of unfolded proteins to Ire1p promotes clustering of this protein and activation of the endonuclease activity of its cytosolic domain. HAC1 mRNAs, themselves attached to multiple ribosomes, are then recruited to the activated Ire1p clusters, and are processed there, allowing translation of the essential stress-response factor Hac1p protein.

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