Part of ribonuclease P, a protein complex that generates mature tRNA molecules by cleaving their 5'-ends. Endonucleolytic cleavage of RNA, removing 5'-extranucleotides from tRNA precursor. kcat 10 min(-1) in absence of L7Ae, 63 min(-1) in presence of L7Ae. Kinetic parameters determined at 37 degrees Celsius. Optimum temperature is 36-38 degrees Celsius in the absence of L7Ae, 48-50 degrees Celsius in presence of L7Ae. Consists of a catalytic RNA component and at least 5 protein subunits. Belongs to the eukaryotic/archaeal RNase P protein component 1 family.