A role for ubiquitinylation and the cytosolic proteasome in turnover of mitochondrial uncoupling protein 1 (UCP1)

► UCP1 is ubiquitinylated in mitochondria from brown adipose tissue and thymus. ► Ubiquitinylated UCP1 is degraded by the cytosolic proteasome. ► The half-life of UCP1 in thymocytes is approximately 3 h. ► Cold-acclimation increases the amount of UCP1 that is ubiquitinylated in BAT.