The endoplasmic reticulum-residing chaperone BiP is short-lived and metabolized through N-terminal arginylation

BiP and other endoplasmic reticulum (ER)–resident proteins are thought to be metabolically stable and to function primarily in the ER lumen. We sought to assess how the abundance of these proteins dynamically fluctuates in response to various stresses and how their subpopulations are relocated to non-ER compartments such as the cytosol. We showed that the molecular chaperone BiP (also known as GRP78) was short-lived under basal conditions and ER stress. The turnover of BiP was in part driv