Question

What are the main features of splicing in pre-tRNA that distinguish it from splicing in pre-mRNA?

Answer 1

In the total RNA, rRNA constitutes 80%, tRNA constitutes 15% and mRNA constitute only 3-5%. All these RNAs after their synthesis needs to undergo processing before getting into their. The processing of these 3 RNAs slightly differ from each other and their modification is solely based on their function what they are going to perform after it.

Pre-mRNA splicing	Pre-tRNA splicing
The eukaryotic pre-mRNA undergoes extensive processing before getting translated	The eukaryotic pre-mRNA will not undergo extensive processing.
A 7-methylguanosine cap is added to the 5' end of the growing transcript by a 5'-to-5' phosphate linkage.	The 5' end of the pre-tRNA (5' leader sequence) is cleaved off during the processing by ribonuclease P (RNase P), a ribonucleoprotein endonuclease.
An enzyme called poly (A) polymerase (PAP) adds a string of approximately 200 A nucleotides, called the poly (A) tail, to the 3' end of the just-cleaved pre-mRNA.	The 3' end of the pre-tRNA is cleaved off and CCA sequence of nucleotides is added to the 3' end of the pre-tRNA.
Contains exons (protein coding sequences) and introns (non coding sequences), spliceosomes removed the introns and joins together the exons. Each spliceosome has five subunits (snRNPs) and these will cut the introns at GU at 3’end and attaches the 3' end of the first exon to the 5' end of the following exon, releasing the intron in a lariat form.	The cleaving of introns will take place in the same manner, but the number of introns present will be less in tRNA and it is absent in the tRNA of prokaryotes.
There is no modification of nucleotides here	12 nucleotides on average per tRNA will be modified chemically by altering their nitorgen bases. Conversion of adenine (A) to pseudouridine (ψ), the conversion of adenine to inosine (I), and the conversion of uridine to dihydrouridine(D).