Medical research

How it works: The protein that stimulates muscle growth

In the gym, you are not just pumping iron, you are oxygenating muscle cells which keeps those muscles healthy, strong and growing—a process called hypertrophy, or an increase in muscle mass due to an increase in muscle ...

Oncology & Cancer

New gene targets for treating adult blood cancer

Hokkaido University scientists have identified new targets for treating an aggressive form of adult leukemia with existing drugs. The findings were published in the journal Blood.

Neuroscience

Neuroscientists identify mechanism for long-term memory storage

A University of Iowa neuroscience research team has identified a fundamental biochemical mechanism underlying memory storage and has linked this mechanism to cognitive deficits in mouse models of Alzheimer's disease and related ...

Medications

Transfer RNA may be a new drug for peripheral neuropathy

A team of scientists led by Erik Storkebaum of Radboud University's Donders Institute have deciphered the molecular mechanism underlying a form of Charcot-Marie-Tooth (CMT) peripheral neuropathy. This disease affects both ...

Gerontology & Geriatrics

Using old and young blood to study age-related muscle loss

An innovative model using human blood samples to study muscle protein growth may help advance scientists' understanding of age-related muscle loss. The study is published ahead of print in the American Journal of Physiology-Cell ...

Medical research

Normally harmless cell molecule triggers neuron death

A vital intermediate in normal cell metabolism is also, in the right context, a trigger for cell death, according to a new study from Wanli Liu and Yonghui Zhang of Tsinghua University, and Yong Zhang of Peking University ...

Medical research

New clues to how muscle wasting occurs in people with cancer

Muscle wasting, or the loss of muscle tissue, is a common problem for people with cancer, but the precise mechanisms have long eluded doctors and scientists. Now, a new study led by Penn State researchers gives new clues ...

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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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