New insights into a fundamental process in mitochondria

Researchers at Karolinska Institutet have uncovered the function of the release factor mtRF1 in the final steps of mitochondrial protein synthesis. The study, published in Nature Communications, reveals new insights into ...

Why synonymous mutations are not always silent

New modeling shows how synonymous mutations—those that change the DNA sequence of a gene but not the sequence of the encoded protein—can still impact protein production and function. A team of researchers led by Penn ...

Efficient mRNA delivery by branched lipids

Messenger RNA (mRNA) are biological molecules that transfer the information coded by genes in the nucleus to the cytoplasm for protein synthesis by ribosomes. mRNA sequences can be designed to encode specific proteins; the ...

Gaining structural insight into the influenza virus

A team of scientists at University of Oxford have worked with multiple techniques at Diamond Light Source, to solve the structure of the influenza replication machinery and to determine how it interacts with cellular proteins. ...

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Protein biosynthesis

Protein synthesis is the process in which cells build proteins. The term is sometimes used to refer only to protein translation but more often it refers to a multi-step process, beginning with amino acid synthesis and transcription of nuclear DNA into messenger RNA which is then used as input to translation.

The cistron DNA is transcribed into a variety of RNA intermediates. The last version is used as a template in synthesis of a polypeptide chain. Proteins can often be synthesized directly from genes by translating mRNA. When a protein is harmful and needs to be available on short notice or in large quantities, a protein precursor is produced. A proprotein is an inactive protein containing one or more inhibitory peptides that can be activated when the inhibitory sequence is removed by proteolysis during posttranslational modification. A preprotein is a form that contains a signal sequence (an N-terminal signal peptide) that specifies its insertion into or through membranes; i.e., targets them for secretion. The signal peptide is cleaved off in the endoplasmic reticulum.. Preproproteins have both sequences (inhibitory and signal) still present.

For synthesis of protein, a succession of tRNA molecules charged with appropriate amino acids have to be brought together with an mRNA molecule and matched up by base-pairing through their anti-codons with each of its successive codons. The amino acids then have to be linked together to extend the growing protein chain, and the tRNAs, relieved of their burdens, have to be released. This whole complex of processes is carried out by a giant multimolecular machine, the ribosome, formed of two main chains of RNA, called ribosomal RNA (rRNA), and more than 50 different proteins. This molecular juggernaut latches onto the end of an mRNA molecule and then trundles along it, capturing loaded tRNA molecules and stitching together the amino acids they carry to form a new protein chain.

Protein biosynthesis, although very similar, is different for prokaryotes and eukaryotes.

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