FEM1A functions as a substrate-recognition component of a CUL2-RING E3 ubiquitin ligase complex that mediates protein degradation through the C-degron pathway 1. The protein contains six ankyrin repeat elements in its N-terminal region, similar to signaling and transcriptional regulatory molecules 2. FEM1A specifically targets proteins for ubiquitination and degradation, including the stem-loop binding protein (SLBP), which regulates histone mRNA metabolism 1. This regulatory function appears evolutionarily conserved, as FEM1A orthologues interact with SLBP in C. elegans and D. melanogaster 1. The gene shows tissue-specific expression patterns, being highly expressed in kidney and cardiac tissue, with lower expression in multiple other tissues including skeletal muscle 2. FEM1A has clinical relevance in several diseases: it is consistently downregulated in rhabdomyosarcoma cell lines and mouse models, suggesting involvement in skeletal muscle differentiation defects 3. Additionally, FEM1A variants are associated with polycystic ovary syndrome (PCOS), with specific polymorphisms linked to hyperandrogenism and insulin resistance 4 5. The protein is also identified as a prognostic marker in gastric cancer 6. These findings indicate FEM1A plays important roles in cellular differentiation, metabolic regulation, and disease pathogenesis.