Component of ribonuclease P, a protein complex that generates mature tRNA molecules by cleaving their 5'-ends. Also a component of RNase MRP, which cleaves pre-rRNA sequences (By similarity). Endonucleolytic cleavage of RNA, removing 5'-extranucleotides from tRNA precursor. Component of nuclear RNase P and RNase MRP complexes. Belongs to the histone-like Alba family.