Ribosomes pile up

Extensive piles of internal membranes accumulate when protein targeting to membranes is interrupted in E. coli, as seen in an article by Herskovits et al. on page 465. The membranes contain ribosomes and a receptor with an early function in ribosome targeting.

The receptor is FtsY, a homologue of the eukaryotic signal recognition particle (SRP) receptor. Recent evidence suggests that, unlike eukaryotes, E. coli do not need SRP for ribosome targeting to the membrane, where membrane proteins will be inserted. However, the process does depend on the receptor FtsY. In the new paper, FtsY function is highlighted.

The result is a visual confirmation that FtsY brings ribosomes to the membrane even in the absence of one of its ligands, the SRP. Herskovits et al. disrupted steps downstream of this event—the transfer of ribosomes to...