Sorting Out the JUNQ: The Spatial Nature of Protein Quality Control

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Cambridge University Press

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Microscopy and Microanalysis

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DOI: 10.1017/s1431927617005633


A healthy proteome is essential for survival, and cells have elaborate protein quality control (PQC) systems to maintain protein homeostasis, or proteostasis [1,2]. PQC systems are comprised of molecular chaperones which identify and bind misfolded proteins then target them for clearance by proteolytic pathways such as the proteasome or autophagy [1]. Increasingly, defects in PQC are linked to human diseases such as Alzheimer’s, Parkinson’s, cancer and even aging [1-2]. One commonality among many of these diseases is the presence of intra- and extra-cellular inclusions containing misfolded proteins, which may result from a breakdown in PQC mechanisms leading to terminal sequestration of misfolded, toxic proteins. This demonstrates a critical need to better understand the complex PQC machinery as well as the mechanisms of inclusion formation and clearance. Misfolded proteins are actively sequestered into a number of distinct PQC compartments that are conserved from yeast to mammals [1]. The juxtanuclear quality-control compartment (JUNQ), which forms when the proteasome is impaired, contains soluble misfolded proteins that can be refolded or cleared [3]. A recent study proposed that the JUNQ actually resides inside the nucleus and should be renamed to INQ [4].


Microscopy and Microanalysis, Vol. 23, No. s1 (July 2017): 994-995. DOI.