22 June 2017

Narrow specialization among ribosomes

Ribosomes were suspected of specializing in the production of certain proteins

Sergey Vasiliev, Naked Science

American biologists have shown that some ribosomes can specialize in the synthesis of proteins of a certain group, giving the cell an additional level of control over metabolism.

It is commonly thought that ribosomes are universal intracellular protein factories that synthesize any chains of amino acids from any matrix RNAs. However, a new study by biologists at Stanford University (California, USA) leads to an unexpected conclusion: ribosomes can be specialized. In the article Simsek et al. The Mammalian Ribo-interactome Reveals Ribosome Functional Diversity and Heterogeneity, published by the journal Cell, Maria Barna and her co-authors write that such specialization could give the cell an additional tool for controlling protein synthesis, and at the same time would explain some rare diseases.

A mammalian cell can contain up to 10 million ribosomes, for which it is ready to spend more than half of its resources. It is believed that they are ready to synthesize any proteins, although scientists have found certain indications of ribosome specialization more than once. For example, mice with a deficiency of one of the protein components of the ribosome are characterized by such developmental abnormalities that may be associated with a lack of a well-defined group of protein growth factors, the synthesis of which is disrupted in them.

In a new work, American biologists determined the exact number of different ribosomal proteins in mouse embryonic stem cells using mass spectrometry. Of the 76 proteins examined, most were found in all ribosomes, but seven were found in some and not in others. Scientists have shown that ribosomes devoid of these proteins work only with matrix RNA of certain types and can be specialized in the production of certain groups of proteins. Apparently, some of these ribosomes synthesize growth factors, others – a group of enzymes necessary for the metabolism of vitamin B12, etc.

The authors note that such specialization could give the cell a new opportunity to control the production of proteins, and would also explain the mechanisms of some rare and severe metabolic disorders. For example, Diamond –Blackfan syndrome, in which erythropoiesis is disrupted in the bone marrow, and microcephaly and finger development defects are observed in newborns, according to the authors, may be associated with a malfunction in the work of ribosomes of a certain specialization.

Portal "Eternal youth" http://vechnayamolodost.ru  22.06.2017

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