The variety of proteins synthesized by a cell and the specific amino acid compositions of each protein are ultimately governed by the cellular DNA. This DNA is enzymatically transcribed in the cell nucleus to produce a host of RNAs, including ribosomal RNA (rRNA), messenger RNA (mRNA), and transfer RNA (tRNA). Different RNA polymerases are responsible for the synthesis of each [...]
Thousands of experiments carried out during the past 25 years involving hundreds of scientists have slowly and painstakingly revealed the intricate details of the mechanism by which proteins are synthesized in prokaryotic and eukaryotic cells. The overwhelming majority of these studies were conducted using two particular kinds of cells, namely, the bacterium E. coli and the mammalian reticulocyte. Bacterial cells [...]
The rate of breakdown and replacement of protein in cells was badly misunderstood prior to 1939. In growing animals generally and in secretory tissues in particular (liver, pancreas, endocrine glands, etc.), active synthesis of protein was known. However, the amount of protein synthesis taking place in other tissues of the adult was believed to be very low and confined to [...]