摘要：SummaryPhosphatidylethanolamine (PE) made in mitochondria has long been recognized as an important precursor for phosphatidylcholine production that occurs in the endoplasmic reticulum (ER). Recently, the strict mitochondrial localization of the enzyme that makes PE in the mitochondrion, phosphatidylserine decarboxylase 1 (Psd1), was questioned. Since a dual localization of Psd1 to the ER would have far-reaching implications, we initiated our study to independently re-assess the subcellular distribution of Psd1. Our results support the unavoidable conclusion that the vast majority, if not all, of functional Psd1 resides in the mitochondrion. Through our efforts, we discovered that mutant forms of Psd1 that impair a self-processing step needed for it to become functional are dually localized to the ER when expressed in a PE-limiting environment. We conclude that severely impaired cellular PE metabolism provokes an ER-assisted adaptive response that is capable of identifying and resolving nonfunctional mitochondrial precursors.Graphical abstractDisplay OmittedHighlights•Functional Psd1, the enzyme that makes PE, is mitochondrial localized•When cellular PE metabolism is impaired, mutant Psd1 is also targeted to the ER•Mutant Psd1 targeted to the ER is ubiquitinated and rapidly degraded•Impaired PE metabolism activates a reversible stress responseMolecular Physiology; Cell Biology; Proteomics
