The 5’ cap (sometimes called the GTP cap or methyl cap) and the poly-A tail helps the mRNA molecule move through the nuclear pore and attacking exonucleases to attach to a ribosome, its final destination. The cap is a modified guanine (G) nucleotide, and it protects the transcript from being broken down. It also helps the ribosome attach to the mRNA and start reading it to make a protein.
