The JUNQ serves as such a sequestration site. It was shown that when the proteasome is impaired (e.g. by low expression levels of the proteasome subunit RPN11), ubiquitinated misfolded proteins are sorted into the JUNQ. Upon recovery from stress conditions (e.g. recovery from heat shock at a permissive temperature), misfolded proteins that accumulate in the JUNQ may be either refolded by the cellular chaperone machinery, or degraded by the 26S proteasome. Thus, the sequestration of a protein to the JUNQ is reversible.
