The molecules responsible for ending the process of protein synthesis are release factors. These proteins recognize stop codons in the messenger RNA (mRNA) and trigger the hydrolysis of the bond between the tRNA and the polypeptide chain, leading to the release of the newly synthesized protein. In eukaryotes, two release factors, eRF1 and eRF3, mediate this termination process. eRF1 recognizes all three stop codons (UAA, UAG, and UGA), while eRF3 is a GTPase that facilitates eRF1 binding and the subsequent termination events.
Effective termination of translation is vital for cellular function. Premature termination can result in truncated and non-functional proteins, while a failure to terminate can lead to ribosome stalling and the production of aberrant proteins. These errors can have detrimental consequences for the cell, including the activation of quality control pathways like nonsense-mediated decay (NMD) which degrade mRNA containing premature stop codons. The accuracy and efficiency of these factors are crucial for maintaining proteome integrity and preventing the accumulation of potentially harmful polypeptides. Research into the structure and function has provided insights into the mechanistic details of translation termination, and these findings have implications for understanding and treating diseases linked to translational errors.
