The term "Peptide Chain Termination" is spelled as /pɛptɑɪd tʃeɪn tɜːrmɪneɪʃən/. The initial "p" is in the voiceless bilabial plosive sound, followed by the short "e" sound represented by "ɛ". The letters "pt" represent the consonant cluster /pt/ which is followed by the long "a" sound, represented by /ɑ/. The rest of the spellings follow similar phonetic representations for their respective sounds. The term refers to the end of a chain of amino acids in a polypeptide, indicating the completion of protein synthesis.
Peptide chain termination refers to the process by which the synthesis of a polypeptide chain, or the assembly of amino acid sequences, is stopped or completed. It involves the release of the newly formed peptide from the ribosome, which is the protein synthesis machinery within cells.
During translation, the ribosome reads the instructions encoded in mRNA (messenger RNA) and binds amino acids together to form a growing peptide chain. The process of chain termination occurs when a stop codon, or termination signal, is encountered on the mRNA. Stop codons, such as UAA, UAG, or UGA, do not code for any specific amino acid but act as signals for the ribosome to cease protein synthesis.
When the ribosome reaches a stop codon, various molecular components, called release factors, recognize the stop codon and trigger the release of the polypeptide chain from the ribosome. Release factors interact with the ribosome and catalyze the hydrolysis of the bond between the newly formed polypeptide chain and the tRNA (transfer RNA) molecule that carried the last amino acid. This detachment of the polypeptide chain from the tRNA marks the completion of protein synthesis.
After the peptide chain is released, it often folds into a specific three-dimensional structure to become a functional protein. Peptide chain termination is a crucial step in protein synthesis, as it ensures the accurate termination of the polypeptide chain and enables the production of functional proteins necessary for various cellular processes.