A regulatory sequence found in the 5' terminal regions of a variety of RNA species. The sequence starts with a CYTIDINE, which is followed by a stretch of 5 to 15 PYRIMIDINE NUCLEOTIDES. Messenger RNA that contains the 5' Terminal Oligo Pyrimidine tract is often referred to as 5' TOP mRNA. The sequence acts as a translational regulator and has been found in mRNAs for PEPTIDE ELONGATION FACTORS and RIBOSOMAL PROTEINS.

The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.