Scientists estimate that our brain consists of about ten to one hundred billions of nerve cells. In order to fulfill their respective tasks as long as possible, these cells have to constantly control their internal proteins with regard to quality and functionality. Otherwise the proteins might clump together and thereby paralyze or even kill the cells. Once the cell recognizes a defect protein, this is marked for degradation and a kind of a molecular shredder, the so-called proteasome, chops it into pieces that are eventually recycled.
The proteasomes (grey) of the nerve cell (neuron) are equipped with the regulatory particles at their ends. These structures change their shape depending on whether they have bound (red) proteins which have to be degraded (green) or not (blue).
Credit:Figure: Shoh Asano / Copyright: MPI of Biochemistry
Asano S, Fukuda Y, Beck F, Aufderheide A, Förster F, Danev R and Baumeister W: A molecular census of 26S proteasomes in intact neurons . Science, January 23, 2015