Recently, scientists at the Max Planck Institute of Biochemistry (MPIB) in Martinsried near Munich, Germany, succeeded in mapping the inner life of an intact human cell three-dimensionally via cryo-electron tomography. In this way they were able to show where the ribosomes are located in the cell and how they are arranged. In the past, this was only possible with bacterial cells. The results have now been published in Molecular Cell.
Human cells are very complex entities with many different components. A very important cellular component are the ribosomes: As the protein factories of the cell, they are responsible for the production of proteins (protein synthesis). The blueprint provides our heritable information, the DNA.
Because of their importance for protein synthesis, the ribosomes have often been subject of structural research. Until now, the scientists could only look at individual, isolated ribosomes. But in the living cell, ribosomes usually appear lined up like pearls on a string, in so-called polyribosomes. An isolated view is not enough to understand completely how the protein production proceeds inside the cell and how it is embedded in the complex cellular structures and processes. Thus it is necessary to map and to investigate the ribosomes in their “natural environment”, in the interior of the cell. This permits cryo-electron tomography.
Now the scientists discovered how the ribosomes are positioned inside the human cell: Their arrangement is clearly non-random but rather makes sure that newly originated, still unfolded proteins keep a big distance between each other. “We could already observe a similar positioning in bacterial cells which suggests that the ribosomes of all human beings are arranged in almost the same manner”, explains Florian Brandt, scientist at the MPIB. “This spatial organization of the ribosomes could probably have the aim to inhibit the aggregation and misfolding of newly originated proteins.”
The work of the MPIB scientists is another important step for cell biology, because it helps to better understand the distribution of cellular components and the spatial organization of the whole cell much better. “In the future it could also be interesting”, says Brandt, “how the organization of ribosomes changes in aging and sick cells and how these changes affect the total efficiency of protein production and folding.” [UD]Original Publication:
Anja Konschak | idw
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