YBEY encodes a highly conserved single strand-specific metalloendoribonuclease that plays critical roles in ribosome biogenesis and RNA processing across diverse biological systems 1. The protein functions primarily in rRNA maturation, particularly processing the 3' end of 16S rRNA and facilitating small ribosomal subunit assembly in association with ribosomal protein uS11 and assembly GTPase Era 1. In human mitochondria, YbeY performs dual functions in precursor RNA processing and mitoribosome biogenesis, with loss of function leading to severe reduction in mitochondrial translation and cell viability 2. The enzyme also regulates small RNA networks, directly degrading regulatory RNAs such as ReaL in Pseudomonas aeruginosa to control downstream gene expression 3. YbeY demonstrates significant disease relevance, with knockdown in breast cancer cell lines decreasing proliferation, colony formation, and migration regardless of estrogen receptor status 4. In pathogenic bacteria, YbeY deletion severely compromises virulence, growth rate, and stress resistance while disrupting secretion systems and biofilm formation 567. Clinical significance is emerging, as genetic variants near YBEY associate with breast cancer risk through altered gene expression 4, and the gene shows interaction effects in sleep apnea genome-wide association studies 8.