Producing F-18 radiopharmaceuticals for PET imaging

Recently ANSTO researchers have made progress investigating improved ways to make life-saving radiopharmaceuticals using the fluorine-18 radioisotope so they can be available in more hospitals at lower cost.

Scientist constructs artificial photosynthetic cells

A team led by associate professor Yutetsu Kuruma of the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology has constructed simple artificial cells that can produce chemical energy that helps synthesize parts ...

Researchers find hidden proteins in bacteria

Scientists at the University of Illinois at Chicago have developed a way to identify the beginning of every gene—known as a translation start site or a start codon—in bacterial cell DNA with a single experiment and, through ...

Sea slug study illuminates how mitochondria move

Your cells have an amazing ability—they can build their own energy factories, called mitochondria. Once built, mitochondria must move where needed in the cell. Defects in mitochondrial transport are a suspected cause of ...

A molecular hammock for cotranslational modification

Proteins do most of the real work in cells and are modified in accordance with functional requirements. An LMU team has now shown how proteins are chemically altered on the ribosome, even before they fold into the active ...

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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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