unfolded protein response

cellular mechanism

Also known as: UPR

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Last updated

June 17, 2026

Quick Summary

The unfolded protein response (UPR) is a cellular mechanism that activates when misfolded or unfolded proteins accumulate in the endoplasmic reticulum (ER). This stress response is adaptive, aiming to restore normal cell function by reducing protein synthesis and increasing the ER's capacity for protein folding and degradation. If these adaptive measures fail, the cell initiates programmed cell death, known as apoptosis. The rough endoplasmic reticulum (RER), studded with ribosomes, is central to protein synthesis and folding. When proteins are not folded correctly within the RER, it triggers the UPR.12

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endoplasmic reticulum
…signaling mechanism known as the unfolded protein response (UPR) is activated. The response is adaptive, such that UPR activation triggers reductions in protein synthesis and enhancements in ER protein-folding capacity and ER-associated protein degradation. If the adaptive response fails, cells are directed to undergo apoptosis (programmed cell death).
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…signaling mechanism known as the unfolded protein response (UPR) is activated. The response is adaptive, such that UPR activation triggers reductions in protein synthesis and enhancements in ER protein-folding capacity and ER-associated protein degradation. If the adaptive response fails, cells are directed to undergo apoptosis (programmed cell death).
Read More