Oncology & Cancer

Study identifies cancer patients most likely to develop cachexia

It is estimated that as many as 80% of advanced-stage cancer patients may develop cachexia, a potentially fatal metabolic syndrome characterized by extreme weight loss and muscle wasting, but scientists do not yet fully understand ...

Psychology & Psychiatry

Scientists discover link between autism and cognitive impairment

Autism can bestow brilliance as well as cognitive difficulty, but how either scenario plays out in the brain is not clear. Now a study by University of Toronto researchers has found that a tiny gene fragment impacts the brain ...

Diseases, Conditions, Syndromes

Toxoplasmosis: Preventing mother-to-child transmission

Professor Maritza Jaramillo knows a thing or two about parasites—she has spent most of her life studying them. "During my bachelor's degree in Colombia, I did an internship at a lab specializing in parasitic infections. ...

Parkinson's & Movement disorders

Genetic markers linked to the start of symptoms of Parkinson's disease

Researchers from the Institute of Neurosciences of the University of Barcelona (UBNeuro), Hospital Clínic and the August Pi i Sunyer Biomedical Research Institute (IDIBAPS) have identified a group of genetic variants related ...

Medical research

Researchers find protein that suppresses muscle repair in mice

Researchers report that a protein known to be important to protein synthesis also influences muscle regeneration and regrowth in an unexpected manner. The discovery, reported in the Journal of Clinical Investigation, could ...

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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.

This text uses material from Wikipedia, licensed under CC BY-SA