The final trimming step — ScienceDaily

Ribosomes synthesize all the proteins in cells. Studies mainly done on yeast have revealed much about how ribosomes are put together, but an Ludwig-Maximilians-Universitaet (LMU) in Munich team now reports that ribosome assembly in human cells requires factors that have no counterparts in simpler model organisms.

In every cell, hundreds of thousands of intricate molecular machines called ribosomes fabricate new proteins, extending each growing chain at a rate of a few amino acids per second. Not surprisingly therefore, the construction of these vital protein factories is itself a highly complex operation, in which more than 200 assembly factors are transiently involved. Mature ribosomes are made up of approximately 80 proteins and four ribosomal RNAs. But how these constituents are assembled in the correct order to yield a functional ribosome is still not fully understood. Moreover, most of our knowledge of the process comes from studies carried out on model organisms

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