Essays Helper: 4 SITES OF PROTEIN SYNTHESIS IN PLANTS …
The polypeptide chain is transferred from the P-site tRNA to the free amino group of the amino acid attached to the A-site tRNA, forming a new peptide bond. This reaction is catalysed by the peptidyl transferase center of the large ribosomal subunit. This reaction is followed by a series of large conformational changes, which shift the two tRNAs into the P and E sites of the large subunit, so the tRNA which previously was in the A-site is now in the P-site and the E-site is bound with the former tRNA of the P-site. Through large conformational changes catalysed by the protein EF-G, the mRNA moves by three nucleotides with respect to the the small ribosomal subunit together with the tRNAs so that the ribosome is ready to enter the next round and accept a new tRNA. These three steps are repeted in a so-called until the ribosome reaches a stop codon, where synthesis is stopped and the protein chain is released. Procaryotic ribosomes are remarkably efficient: within a bacterial cell, one ribosome can add 20 amino acids to a growing polypeptide chain every second.
The ribosome is helped both at the start and end of translation by specialized proteins called initiation factors and release factors, respectively.
At the beginning of protein synthesis, ..
Protein synthesis is the process whereby biological ..
Outline of pathways of synthesis of nonessential amino acids. Modified from Munro HM (ed.) (1969) Evolution of protein metabolism in mammals. In: , vol. 3, pp. 133–182. New York: Academic Press.
The rate of protein synthesis is higher in ..
Components of the protein synthesizing machinery specific for mitochondria-ribosomes, tRNAs and specific proteins and enzymes-are also found in the matrix.
Modification of protein synthesis enables plants to mount an ..
Amino acids are classically considered as the building blocks from which proteins are synthesised. Besides this, some of them play a major role in the regulation of protein turnover and signal transduction, transport of nitrogen and carbon across the organs, and neurotransmission.
The efficiency of protein synthesis in ..
In the human adult as much as 200–250 g of proteins are degraded daily, and their constituent amino acids are in large part reutilised in protein synthesis.