RNAs involved in protein biosynthesis
Information flow in the cell: DNA is transcribed to mRNA which is translated (decoded as) into Protein. Protein biosynthesis takes place in the ribosomes. A series of ribosomes (poly ribosome) can simultaneously translate the same eukaryotic mRNA molecule. tRNA brings specific amino acid to ribosome and mRNA carries the genetic information to protein. Codons that encode the same amino acid often differ only by their third base. The binding of the third base is less stringent than the other two. Because of this wobble, one tRNA can pair with multiple mRNA codons.
Process of protein biosynthesis
There are signal sequences before the real coding sequence at the translation initiation sites. Amino acid activation is catalyzed by amino acyl-tRNA synthetase and couples it to its corresponding tRNA. Anti codon in tRNA molecule forms base pairs with the appropriate codon on the mRNA. In the initiation step, initiation factors are involved. Initiation factor is the protein that promotes the proper association of ribosomes with messenger RNA. In the elongation step, incorporation of an amino acid into a protein takes place. As a result, polypeptide chain is grown. Termination is the last stage in protein biosynthesis.
Quality control and chaperones
If at all, a wrong amino acid is added, tRNA synthetase removes the incorrectly attached amino acid through hydrolytic editing. There are protein molecules called chaperones that catalyze the correct folding of other proteins within the cell. They also help in preventing aggregation. The hsp70 family of molecular chaperones helps in correct folding after synthesis.
