FXR1 (FMR1 autosomal homolog 1) is an RNA-binding protein that regulates mRNA translation and stability through multiple mechanisms critical for development and cellular homeostasis. The protein specifically binds to AU-rich elements (AREs) in the 3'-UTR of target mRNAs and undergoes liquid-liquid phase separation (LLPS) to form cytoplasmic ribonucleoprotein granules that concentrate mRNAs with regulatory factors 1. During spermatogenesis, FXR1 activates translation of stored mRNAs in late spermatids by recruiting translation initiation factor EIF4G3 through LLPS, and germline-specific ablation causes male infertility 1. FXR1 forms an extensive cytoplasmic mRNA-protein network that serves as a signaling scaffold, maintaining spatial proximity between kinases and substrates essential for actomyosin reorganization and cell shape regulation 2. The protein interacts with various mRNA metabolism regulators including YBX1, YBX2, PABPC1, and EIF4G3 3. FXR1 can both stabilize mRNAs (such as OTUB1 in lung cancer) and promote mRNA degradation (PDZK1IP1 and ATOH8 in esophageal cancer), demonstrating context-dependent regulatory functions 45. Mutations in FXR1 are associated with congenital myopathies, highlighting its essential role in muscle development and function.