Dear Dr Shakir M. S. Alfahdawi . Post-translational modification can occur at any step in the "life cycle" of a protein. For example, many proteins are modified shortly after translation is completed to mediate proper protein folding or stability or to direct the nascent protein to distinct cellular compartments (e.g., nucleus, membrane). See the link: https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-biology-learning-center/protein-biology-resource-library/pierce-protein-methods/overview-post-translational-modification.html

Kindly see also the following RG link: Article Importance of post-translational modifications on the functi...

Also check please the following useful RG link: Chapter Translation and Post-translational Modifications in Protein ...

The following link is very useful: https://www.sciencedirect.com/topics/neuroscience/posttranslational-modification

ما المقصود من ذلك

د. ابراهيم سلمان الموسوي , added a reply on January 13, 2022, as follows:

ما المقصود من ذلك

Transliteration: ma almaqsud min dhalik

Translation from Arabic to English, as follows:

"What is the meaning of that"

Source: Artificially-Intelligent Translator

Proteins are synthesized by ribosomes translating mRNA into polypeptide chains, which may then undergo PTM to form the mature protein product. PTMs are important components in cell signaling, as for example when prohormones are converted to hormones. Post-translational modifications can occur on the amino acid side chains or at the protein's C- or N- termini. They can extend the chemical repertoire of the 20 standard amino acids by modifying an existing functional group or introducing a new one such as phosphate.

https://en.wikipedia.org/wiki/Post-translational_modification

Also. kindly check:

https://advansta.com/wikis/posttranslational-modifications-protein-phosphorylation/