Fbx32 is an E3 ubiquitin ligase that initiates ATP dependent ubiquitin-mediated proteolysis and promotes muscle atrophy. It is highly expressed during muscle atrophy, whereas mice deficient in this gene were found to be resistant to atrophy. It is also thought to recognize and bind to some phosphorylated proteins and promote their ubiquitination and degradation during skeletal muscle atrophy. Fbx32 interacts with MyoD by ubiquitination via a sequence found in transcriptional coactivators and therefore may play an important role in the course of muscle differentiation by determining the abundance of MyoD.