Some of the major stages of Protein Synthesis are: (a) Activation of amino acids, (b) Transfer of amino acid to tRNA, (c) Initiation of polypeptide chain, (d) Chain Termination, (e) Protein translocation

There are five major stages in protein synthesis each requiring a number of components in E. coli and other prokaryotes.

(a) Activation of amino acids: Amino acid-ATP binding causes this process. Amino acyI RNA synthetases are needed. Due to this enzyme-mediated interaction between amino acid (AA) and ATP, amino acyl-AMP-enzyme complex is generated .

(b) Amino acid transfer to tRNA AA-AMP-enzyme complex reacts with tRNA. tRNA receives amino acid. Enzyme and AMP are freed.

(c) Initiation of polypeptide chain: Charged tRNA is ribosomal. RNAs and 80 proteins make up the ribosome. Ribosomes synthesise proteins. mRNA interacts to the 70S SOS subunit.

(d) Chain Termination: One of the mRNA's terminal triplets (codons) signals polypeptide termination. UAG, UAA, and UGA are terminal codons (Opal). They're called stoplights.

(e) Protein translocation: Two classes of poly­ribosomes have been identified

Golgi body vesicles include a few lumen-released proteins. They may glycosylate, or add sugar residues. Vesicles merge with plasma membrane, releasing proteins.