Research Highlights

摘要

The three-dimensional structure of the polysome has been elucidated in bacteria. Polysomes are clusters of ribosomes, the cell's protein factories. The ribosomes that make up a polysome (pictured) simultaneously read the same message, so many proteins can be made at the same time. On each ribosome the newly made protein emerges through a specialized polypeptide exit tunnel. Ulrich Hartl and Wolfgang Baumeister at the Max Planck Institute of Biochemistry in Martinsried, Germany, and their colleagues used cryoelectron tomography to show that the ribosomes sit in either a staggered or a helical arrangement so that the exit tunnels are distant from each other. They suggest this minimizes the chance of new proteins sticking to each other.