biostudies-literatureWang WNHLBI NIH HHSe39-e56https://www.ebi.ac.uk/biostudies/studies/S-EPMC11264309biostudies-literatureUnknown135(3)<h4>Background</h4>Clearance of damaged mitochondria via mitophagy is crucial for cellular homeostasis. Apart from Parkin, little is known about additional Ub (ubiquitin) ligases that mediate mitochondrial ubiquitination and turnover, particularly in highly metabolically active organs such as the heart.<h4>Methods</h4>In this study, we have combined in silico analysis and biochemical assay to identify CRL (cullin-RING ligase) 5 as a mitochondrial Ub ligase. We generated cardiomyocytes and mice lacking RBX2 (RING-box protein 2; also known as SAG [sensitive to apoptosis gene]), a catalytic subunit of CRL5, to understand the effects of RBX2 depletion on mitochondrial ubiquitination, mitophagy, and cardiac function. We also performed proteomics analysis and RNA-sequencing analysis to define thCirculation researchUbiquitin Ligase RBX2/SAG Regulates Mitochondrial Ubiquitination and Mitophagy.PMC11264309R01 HL173796R01 HL165205R01 HL146807R01 HL124248Wen YQu CZou JLiu JLi JLi ESun YSu HIslam MSAyala JWeintraub NLFulton DJRWang WLiang QZhou JfalseUbiquitin Ligase RBX2/SAG Regulates Mitochondrial Ubiquitination and Mitophagy.<h4>Background</h4>Clearance of damaged mitochondria via mitophagy is crucial for cellular homeostasis. Apart from Parkin, little is known about additional Ub (ubiquitin) ligases that mediate mitochondrial ubiquitination and turnover, particularly in highly metabolically active organs such as the heart.<h4>Methods</h4>In this study, we have combined in silico analysis and biochemical assay to identify CRL (cullin-RING ligase) 5 as a mitochondrial Ub ligase. We generated cardiomyocytes and mice lacking RBX2 (RING-box protein 2; also known as SAG [sensitive to apoptosis gene]), a catalytic subunit of CRL5, to understand the effects of RBX2 depletion on mitochondrial ubiquitination, mitophagy, and cardiac function. We also performed proteomics analysis and RNA-sequencing analysis to define th2024-01-01T00:00:00Z2024 Jul2026-07-15T10:48:10.811Z2025-08-17T03:05:50.84ZS-EPMC112643093887375810.1161/circresaha.124.32428510.1161/CIRCRESAHA.124.324285