What are the functions of (i) methylated guanosine cap, and (ii) poly-A "tail" in a mature RNA?
The function of Methylated Guanosine Cap: It regulates the nuclear export of mRNA. It promotes translation. They also play a role in proper pre-mRNA splicing by interacting with splicing machinery. Apart from this helps in the export of the mRNA from the nucleus to the cytoplasm.
The function of Poly-A Tail: Plays an important role in transcription termination. It also prevents degradation by increasing mRNA lifespan through protection from exonucleases. Apart from this it also aids in efficient translation by interacting with poly(A)-binding proteins and ribosomes.