RNaseP catalyzes the removal of the 5'-leader sequence from pre-tRNA to produce the mature 5'-terminus. It can also cleave other RNA substrates such as 4.5S RNA. The protein component plays an auxiliary but essential role in vivo by binding to the 5'-leader sequence and broadening the substrate specificity of the ribozyme. Endonucleolytic cleavage of RNA, removing 5'-extranucleotides from tRNA precursor. Consists of a catalytic RNA component (M1 or rnpB) and a protein subunit. Belongs to the RnpA family. Extended N-terminus.