POP5 is a protein subunit of ribonuclease P (RNase P) and ribonuclease MRP (RNase MRP) complexes, two essential ribonucleoprotein enzymes involved in RNA processing 1. In RNase P, POP5 participates in the maturation of transfer RNA (tRNA) molecules by cleaving their 5' leader sequences 12. As a component of RNase MRP, it contributes to the processing of precursor ribosomal RNA (pre-rRNA) 13. Structurally, POP5 folds into an RNA recognition motif (RRM)-like domain and functions within a heteromeric complex where it interacts with RNase P/MRP RNA through its C-terminal helix, serving as a molecular recognition element 4. The protein is evolutionarily conserved across eukaryotes and archaea, with orthologs showing functional interchangeability 56. Beyond its classical role in RNA processing, recent genome-wide association studies validated POP5 as a regulator of telomere length in blood and immune cells; overexpression of POP5 lengthened telomeres in cell lines, indicating an unexpected role in telomere maintenance 7. POP5 localizes to the nucleus and accumulates in the nucleolus, consistent with its involvement in ribosomal and transfer RNA biogenesis 1.